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    <loc>https://en.etudes.ru/etudes/parallelogram/</loc>
    <lastmod>2022-05-31</lastmod>
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      <image:title><![CDATA[Parallelogram]]></image:title>
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      <image:title><![CDATA[Drafting table]]></image:title>
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    <loc>https://en.etudes.ru/etudes/pythagorean-theorem-windmill-proof/</loc>
    <lastmod>2021-01-19</lastmod>
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      <image:title><![CDATA[Pythagorean Theorem: Euclid's proof]]></image:title>
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    <loc>https://en.etudes.ru/etudes/geometric-progression-chess/</loc>
    <lastmod>2020-04-13</lastmod>
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      <image:title><![CDATA[Geometric progression: the chess legend]]></image:title>
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      <video:description><![CDATA[The history of the legend about the chess invention and its vizualisation.]]></video:description>
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    <loc>https://en.etudes.ru/etudes/snell/</loc>
    <lastmod>2020-03-29</lastmod>
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      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/03@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/03.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/04@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/04.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/05@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/05.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/06@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/06.jpg</image:loc>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/07@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/07.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/08@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/08.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/09@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/09.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/10@hd.jpg</image:loc>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/10.jpg</image:loc>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/11@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/11.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/12@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/12.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/snell/13@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/13@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/13.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/14@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/14@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/14.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/15@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/15@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/15.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/16@fhd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/16@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/16.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
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      <video:title><![CDATA[Snell’s Law]]></video:title>
      <video:description><![CDATA[Which pot seems to be deeper - an empty one or filled with water? How does optical fibre work? The mathematics behind these questions is Snell’s law and the properties of sine.]]></video:description>
      <video:duration>139</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/kaleidoscope/</loc>
    <lastmod>2019-03-29</lastmod>
    <image:image>
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      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/01@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/01.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/02@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/02.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/03@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/03.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/04@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/04.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/05@fhd.jpg</image:loc>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/05@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/05.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/06@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/06.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/07@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/07.jpg</image:loc>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/08@fhd.jpg</image:loc>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/08@hd.jpg</image:loc>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/08.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/09@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/09.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/10@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/10.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/11@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/11.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/12@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/12.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/13@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/13@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/13.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/14@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/14@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/14.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/15@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/15@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/15.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/16@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/16@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/16.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:title><![CDATA[Kaleidoscope]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/17@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/17.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/18@fhd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/18@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/18.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
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      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/kaleidoscope/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Kaleidoscope]]></video:title>
      <video:description><![CDATA[The Kaleidoscope, a well-known toy from childhood, turns out to be entirely determined by mathematics.]]></video:description>
      <video:duration>469</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/helix/</loc>
    <lastmod>2017-12-29</lastmod>
    <image:image>
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      <image:title><![CDATA[Helix]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/01@hd.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/01.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/02@hd.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Helix]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/03@hd.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/helix/03.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/04@hd.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/04.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/05@hd.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/05.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/06@hd.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/06.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
    </image:image>
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      <video:title><![CDATA[Helix]]></video:title>
      <video:description><![CDATA[Why can a nut be screwed onto a thread? The reason is that the helix — the base of threaded joints — is uniform at all points.]]></video:description>
      <video:duration>96</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/rainbow/</loc>
    <lastmod>2017-06-29</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/01@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/01.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/02@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/02.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/03@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/03.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/04@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/04.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/05@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/05.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/06@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/06.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/07@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/07.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/08@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/08.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/09@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/09.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/10@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/10.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/11@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/11.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/12@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/12.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/13@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/13@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/13.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/14@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/14@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/14.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/15@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/15@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/15.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/16@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/16@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/16.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/17@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/17@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/17.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/18@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/18@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/18.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/19@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/19@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/19.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/20@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/20@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/20.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/21@fhd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/21@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/21.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_rainbow@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/rainbow/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Rainbow]]></video:title>
      <video:description><![CDATA[The rainbow is such a remarkable phenomenon of nature, and its cause has been so meticulously sought after by inquiring minds... (Rene Descartes)]]></video:description>
      <video:duration>200</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/archimedes/</loc>
    <lastmod>2017-03-29</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/01@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/01.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/02@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/02.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/03@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/03.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/04@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/04.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/05@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/05.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/06@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/06.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/07@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/07.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/08@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/08.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/09@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/09.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/10@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/10.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/11@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/11.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/12@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/12.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_Archimedes@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/archimedes/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Sphere volume: Archimedes Scales]]></video:title>
      <video:description><![CDATA[The cylinder, which has as its base the largest circle of the sphere, and a height equal to its cross-section, is one and a half of the sphere; and its surface is one and a half of the surface of the sphere.]]></video:description>
      <video:duration>161</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/geometric-progression-gears/</loc>
    <lastmod>2017-02-07</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/01@hd.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/01.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/02@hd.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/02.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/03@hd.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/03.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/04@hd.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/04.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/05@hd.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/05.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_geometric-progression-gears@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Geometric progression decrease]]></video:title>
      <video:description><![CDATA[A visual demonstration of a geometric progression decrease.]]></video:description>
      <video:duration>156</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/platonic-solids-harmony/</loc>
    <lastmod>2013-10-25</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/01@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/01.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/02@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/02.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/03@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/03.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/04@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/04.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/05@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/05.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/06@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/06.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/07@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/07.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/08@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/08.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/09@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/09.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/10@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/10.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/11@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/11.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/12@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/12.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/13@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/13@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/13.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/14@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/14@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/14.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/15@fhd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/15@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/15.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_platonic-solids-harmony@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Regular polyhedra harmony]]></video:title>
      <video:description><![CDATA[Regular polyhedrons have been the subject of interest for many great scientists. Perhaps it was the beauty and harmony of the regular polyhedrons that made scientists of the past suggest some kind of deeper purpose for them than just geometric objects.]]></video:description>
      <video:duration>244</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/shukhov-tower/</loc>
    <lastmod>2012-03-14</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/01@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/01.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/02@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/02.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/03@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/03.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/04@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/04.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/05@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/05.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/06@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/06.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/07@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/07.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/08@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/08.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/09@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/09.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/10@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/10.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/11@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/11.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/12@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/12.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/13@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/13@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/13.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/14@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/14@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/14.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/15@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/15@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/15.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/16@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/16@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/16.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/17@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/17@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/17.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/18@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/18@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/18.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/19@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/19@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/19.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/20@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/20@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/20.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/21@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/21@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/21.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/22@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/22@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/22.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/23@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/23@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/23.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/24@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/24@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/24.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/25@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/25@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/25.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/26@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/26@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/26.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/27@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/27@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/27.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/28@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/28@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/28.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/29@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/29@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/29.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/30@fhd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/30@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/30.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_Shukhov-tower@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/shukhov-tower/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Shukhov Tower]]></video:title>
      <video:description><![CDATA[Historical reconstruction of the construction of V.G. Shukhov's tower on Shabolovka in 1919-1922]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/train-wheelset/</loc>
    <lastmod>2011-10-13</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/01@fhd.jpg</image:loc>
      <image:title><![CDATA[A tunnel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/01@hd.jpg</image:loc>
      <image:title><![CDATA[A tunnel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/01.jpg</image:loc>
      <image:title><![CDATA[A tunnel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/02@hd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/02.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/03@hd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/03.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/04@fhd.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/04@hd.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/04.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/05@fhd.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/05@hd.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/05.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/06@fhd.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/06@hd.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/06.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/07@fhd.jpg</image:loc>
      <image:title><![CDATA[The passage in a bend]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/07@hd.jpg</image:loc>
      <image:title><![CDATA[The passage in a bend]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/07.jpg</image:loc>
      <image:title><![CDATA[The passage in a bend]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/08@fhd.jpg</image:loc>
      <image:title><![CDATA[The passage in a bend]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/08@hd.jpg</image:loc>
      <image:title><![CDATA[The passage in a bend]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/08.jpg</image:loc>
      <image:title><![CDATA[The passage in a bend]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/09@fhd.jpg</image:loc>
      <image:title><![CDATA[The passage in a bend]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/09@hd.jpg</image:loc>
      <image:title><![CDATA[The passage in a bend]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/09.jpg</image:loc>
      <image:title><![CDATA[The passage in a bend]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/10@fhd.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels: GOST]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/10@hd.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels: GOST]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/10.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels: GOST]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/11@fhd.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels: GOST]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/11@hd.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels: GOST]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/11.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels: GOST]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/12@fhd.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/12@hd.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/12.jpg</image:loc>
      <image:title><![CDATA[A pair of wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/13@fhd.jpg</image:loc>
      <image:title><![CDATA[Cart]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/13@hd.jpg</image:loc>
      <image:title><![CDATA[Cart]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/13.jpg</image:loc>
      <image:title><![CDATA[Cart]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/14@fhd.jpg</image:loc>
      <image:title><![CDATA[Cart]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/14@hd.jpg</image:loc>
      <image:title><![CDATA[Cart]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/14.jpg</image:loc>
      <image:title><![CDATA[Cart]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/15@fhd.jpg</image:loc>
      <image:title><![CDATA[Train wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/15@hd.jpg</image:loc>
      <image:title><![CDATA[Train wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/15.jpg</image:loc>
      <image:title><![CDATA[Train wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/16@fhd.jpg</image:loc>
      <image:title><![CDATA[Cart]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/16@hd.jpg</image:loc>
      <image:title><![CDATA[Cart]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/16.jpg</image:loc>
      <image:title><![CDATA[Cart]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_train-wheelset@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/train-wheelset/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Train wheels]]></video:title>
      <video:description><![CDATA[Do two train wheels cover the same ride, when spin with the same angular velocity? We will discover that the answer is no! For example, this happens for the wheels of a train wagon in a bend.]]></video:description>
      <video:duration>257</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/invisible-body/</loc>
    <lastmod>2010-12-21</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/01@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/01.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/02@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/02.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/03@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/03.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/04@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/04.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/05@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/05.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/06@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/06.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/07@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/07.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/08@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/08.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/09@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/09.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/10@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/10.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/11@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/11.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/12@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/12.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/13@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/13@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/13.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/14@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/14@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/14.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/15@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/15@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/15.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/16@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/16@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/16.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/17@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/17@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/17.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/18@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/18@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/18.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/19@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/19@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/19.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/20@fhd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/20@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/20.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_invisible-body@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/invisible-body/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Invisible body]]></video:title>
      <video:description><![CDATA[Do invisible bodies exist? That they exist was discovered in 2009 by some mathematicians.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/windscreen-wiper/</loc>
    <lastmod>2010-11-15</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/windscreen-wiper/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Hinge mechanisms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/windscreen-wiper/01@hd.jpg</image:loc>
      <image:title><![CDATA[Hinge mechanisms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/windscreen-wiper/01.jpg</image:loc>
      <image:title><![CDATA[Hinge mechanisms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/windscreen-wiper/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Hinge mechanisms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/windscreen-wiper/02@hd.jpg</image:loc>
      <image:title><![CDATA[Hinge mechanisms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/windscreen-wiper/02.jpg</image:loc>
      <image:title><![CDATA[Hinge mechanisms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/windscreen-wiper/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Hinge mechanisms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/windscreen-wiper/03@hd.jpg</image:loc>
      <image:title><![CDATA[Hinge mechanisms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/windscreen-wiper/03.jpg</image:loc>
      <image:title><![CDATA[Hinge mechanisms]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_windscreen-wiper@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/windscreen-wiper/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Hinge mechanisms]]></video:title>
      <video:description><![CDATA[Everyone has seen how the car windscreen wipers sweep the water away quickly. If you show the mechanism of this system to a mechanic he will tell you that it cannot work!]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/napkin-folding-problem/</loc>
    <lastmod>2010-11-11</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/01@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/01.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/02@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/02.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/03@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/03.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/04@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/04.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/05@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/05.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/06@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/06.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/07@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/07.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/08@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/08.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/09@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/09.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/10@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/10.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/11@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/11.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/19@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
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    <image:image>
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      <video:description><![CDATA[How to fold a rectangular sheet of paper (banknote) so that the perimeter of the resulting polygon is more than the perimeter of the source one?]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
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    <loc>https://en.etudes.ru/etudes/ham-sandwich-theorem/</loc>
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      <image:title><![CDATA[Sandwich problem]]></image:title>
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      <image:title><![CDATA[Sandwich problem]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/ham-sandwich-theorem/13@hd.jpg</image:loc>
      <image:title><![CDATA[Sandwich problem]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/ham-sandwich-theorem/13.jpg</image:loc>
      <image:title><![CDATA[Sandwich problem]]></image:title>
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      <image:loc>https://en.etudes.ru/.data/etudes/ham-sandwich-theorem/14@fhd.jpg</image:loc>
      <image:title><![CDATA[Sandwich problem]]></image:title>
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      <image:title><![CDATA[Sandwich problem]]></image:title>
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      <image:title><![CDATA[Sandwich problem]]></image:title>
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      <image:title><![CDATA[Sandwich problem]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Sandwich problem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ham-sandwich-theorem/16.jpg</image:loc>
      <image:title><![CDATA[Sandwich problem]]></image:title>
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      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/ham-sandwich-theorem/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Sandwich problem]]></video:title>
      <video:description><![CDATA[Can you cut by a planar section a sandwich consisting of a slice of bread, a slice of cheese and a slice of ham in such a way that both sides contain the same amounts of bread, cheese and ham?]]></video:description>
      <video:duration>377</video:duration>
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    <lastmod>2010-09-01</lastmod>
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      <image:title><![CDATA[Continuity]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Continuity]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Continuity]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Continuity]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Continuity]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Continuity]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/continuity/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Continuity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/continuity/03@hd.jpg</image:loc>
      <image:title><![CDATA[Continuity]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Continuity]]></image:title>
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      <video:description><![CDATA[Our observation of the world, based since our infancy on the concept of continuity, appears to be a powerful tool used in the proofs of some mathematical propositions.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
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    <loc>https://en.etudes.ru/etudes/vernier/</loc>
    <lastmod>2010-02-25</lastmod>
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      <image:title><![CDATA[Vernier scale]]></image:title>
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      <image:title><![CDATA[Vernier scale]]></image:title>
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      <image:title><![CDATA[Vernier scale]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Vernier scale]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vernier/02@hd.jpg</image:loc>
      <image:title><![CDATA[Vernier scale]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vernier/02.jpg</image:loc>
      <image:title><![CDATA[Vernier scale]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vernier/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Vernier scale]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vernier/03@hd.jpg</image:loc>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vernier/03.jpg</image:loc>
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      <image:loc>https://en.etudes.ru/.data/etudes/vernier/04@fhd.jpg</image:loc>
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      <image:loc>https://en.etudes.ru/.data/etudes/vernier/04@hd.jpg</image:loc>
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      <image:loc>https://en.etudes.ru/.data/etudes/vernier/06@hd.jpg</image:loc>
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      <image:loc>https://en.etudes.ru/.data/etudes/vernier/06.jpg</image:loc>
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      <image:loc>https://en.etudes.ru/.data/etudes/vernier/07@fhd.jpg</image:loc>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vernier/07@hd.jpg</image:loc>
      <image:title><![CDATA[Vernier scale]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vernier/07.jpg</image:loc>
      <image:title><![CDATA[Vernier scale]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vernier/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Vernier scale]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vernier/08@hd.jpg</image:loc>
      <image:title><![CDATA[Vernier scale]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vernier/08.jpg</image:loc>
      <image:title><![CDATA[Vernier scale]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_vernier@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/vernier/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Vernier scale]]></video:title>
      <video:description><![CDATA[We will show how an additional scale can increase the precision of the measurements.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/pick-theorem/</loc>
    <lastmod>2010-01-25</lastmod>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/tchebyshev-wheelchair/</loc>
    <lastmod>2009-12-29</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/01@hd.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/01.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/02@hd.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/02.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/03@hd.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/03.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/04@hd.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/04.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/TchebRu_wheelchair@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Wheelchair]]></video:title>
      <video:description><![CDATA[]]></video:description>
      <video:duration>0</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/pythagorean-theorem/</loc>
    <lastmod>2009-12-25</lastmod>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/wheel-inventing/</loc>
    <lastmod>2009-10-09</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/01@hd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/01.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/02@hd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/02.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/03@hd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/03.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/04@hd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/04.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/05@hd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/05.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/06@hd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/06.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/07@hd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/07.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/08@hd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/08.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/09@hd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/09.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_wheel-inventing@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/wheel-inventing/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Inventing the wheel]]></video:title>
      <video:description><![CDATA[Can a carriage with non-circular wheels ride along the even surface without jolting?]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/catenary/</loc>
    <lastmod>2009-05-25</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/01@hd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/01.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/02@hd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/02.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/03@hd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/03.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/04@hd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/04.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/05@hd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/05.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/06@hd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/06.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/07@hd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/07.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/08@hd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/08.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/09@hd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/09.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/10@hd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/10.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/11@hd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/11.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_catenary@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/catenary/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Catenary]]></video:title>
      <video:description><![CDATA[Are you able to move over not round wheels?]]></video:description>
      <video:duration>88</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/steering-geometry/</loc>
    <lastmod>2009-03-26</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/01@hd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/01.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/02@hd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/02.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/03@hd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/03.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/04@hd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/04.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/05@hd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/05.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/06@hd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/06.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/07@hd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/07.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Flexible polyhedra]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/flexible-polyhedra/22@hd.jpg</image:loc>
      <image:title><![CDATA[Flexible polyhedra]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/flexible-polyhedra/22.jpg</image:loc>
      <image:title><![CDATA[Flexible polyhedra]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_flexible-polyhedra@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/flexible-polyhedra/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Flexible polyhedra]]></video:title>
      <video:description><![CDATA[Are there closed flexible polyhedra?]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/monge-theorem/</loc>
    <lastmod>2009-03-23</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/monge-theorem/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Leaving the plane]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/monge-theorem/01@hd.jpg</image:loc>
      <image:title><![CDATA[Leaving the plane]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Leaving the plane]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/monge-theorem/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Leaving the plane]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Leaving the plane]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/monge-theorem/02.jpg</image:loc>
      <image:title><![CDATA[Leaving the plane]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/monge-theorem/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Leaving the plane]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/monge-theorem/03@hd.jpg</image:loc>
      <image:title><![CDATA[Leaving the plane]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/monge-theorem/03.jpg</image:loc>
      <image:title><![CDATA[Leaving the plane]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_Monge-theorem@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/monge-theorem/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Leaving the plane]]></video:title>
      <video:description><![CDATA[Considering the ambient space we can often learn more about some object.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/ball-volume/</loc>
    <lastmod>2008-11-27</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/01@hd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/01.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/02@hd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/02.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/03@hd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/03.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/04@hd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/04.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/05@hd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/06@hd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/06.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/07@hd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/07.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_ball-volume@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/ball-volume/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Ball volume]]></video:title>
      <video:description><![CDATA[When you buy an orange with a thick peel, you pay generally for the rind.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
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    <loc>https://en.etudes.ru/etudes/shadows/</loc>
    <lastmod>2008-10-02</lastmod>
    <image:image>
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      <image:title><![CDATA[Shadows]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/01@hd.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
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    </image:image>
    <image:image>
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      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
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    <image:image>
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      <image:loc>https://en.etudes.ru/.data/etudes/shadows/03@fhd.jpg</image:loc>
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      <image:title><![CDATA[Shadows]]></image:title>
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      <image:title><![CDATA[Shadows]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Shadows]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/04.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Shadows]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/05.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/06@hd.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/06.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/07@hd.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/07.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/08@hd.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/08.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/09@hd.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/09.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_shadows@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/shadows/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Shadows]]></video:title>
      <video:description><![CDATA[Let three orthogonal projections of a body are squares. Does the body have to be a cube?]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/axioms/</loc>
    <lastmod>2008-09-18</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/01@hd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/01.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/02@hd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/02.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/03@hd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/03.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/04@hd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/04.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/05@hd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/05.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/06@hd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/06.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_axioms@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/axioms/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Axioms]]></video:title>
      <video:description><![CDATA[Which stool is more steady on the uneven floor — with four or three legs?]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/tchebyshev-sorting-mechanism/</loc>
    <lastmod>2008-06-25</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/01@hd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/01.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/02@hd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/02.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/03@hd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/03.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/04@hd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/04.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/05@hd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/05.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/06@hd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/06.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/07@hd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/07.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/08@hd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/08.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/09@hd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/09.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/10@hd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/10.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/TchebRu_sorting-mechanism@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Sorting mechanism]]></video:title>
      <video:description><![CDATA[]]></video:description>
      <video:duration>0</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/translation-rotation/</loc>
    <lastmod>2008-06-02</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/01@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/01.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/02@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/02.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/03@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/03.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/04@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/04.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/05@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/05.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/06@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/06.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/07@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/07.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/08@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/08.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/09@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/09.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/10@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/10.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/11@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/11.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/12@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/12.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_translation-rotation@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/translation-rotation/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Translation and rotation]]></video:title>
      <video:description><![CDATA[Lift the sheet and leave it fall randomly on the table without turning round. To match initial and final positions one almost surely just need to rotate the sheet around some point to some angle!]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/underground/</loc>
    <lastmod>2008-05-21</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/01@fhd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/01@hd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/01.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/02@fhd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/02@hd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/02.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/03@fhd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/03@hd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/03.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/04@fhd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/04@hd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/04.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/05@fhd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/05@hd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/05.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/06@fhd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/06@hd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/06.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_underground@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/underground/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[How deep is the underground station]]></video:title>
      <video:description><![CDATA[The escalator of the metropolitan railway... How many things are hidden behind these words for a curious observer. How to estimate the depth of a subway station, which is accessed via an escalator? It happens that even to answer this question the knowledge of mathematics can be very useful!]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/angle-trisection/</loc>
    <lastmod>2008-03-01</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/01@hd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/01.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/02@hd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/02.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/03@hd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/03.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/04@hd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/04.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/05@hd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/05.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/06@hd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/06.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/07@hd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/07.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/08@hd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/08.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/09@hd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/09.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_angle-trisection@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/angle-trisection/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Angle trisection]]></video:title>
      <video:description><![CDATA[The problem of the division of an arbitrary angle into three equal angles using only compass and straightedge was proved impossible. But there exists a plane linkage that solve this problem.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/degrees-of-freedom/</loc>
    <lastmod>2008-02-21</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/01@hd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/01.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/02@hd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/02.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/03@hd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/03.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/04@hd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/04.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/05@hd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/05.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/06@hd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/06.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_degrees-of-freedom@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Degrees of freedom]]></video:title>
      <video:description><![CDATA[Does every mechanism has a number of degrees of freedom «fixed»? Or there are mechanisms whose number of degrees of freedom is variable? It turns out that there are…]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/lipkin-inversor/</loc>
    <lastmod>2008-01-11</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/01@hd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/01.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/02@hd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/02.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/03@hd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/03.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/04@hd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/04.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/05@hd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/05.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/06@hd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/06.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/07@hd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/07.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/08@hd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/08.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_Lipkin-inversor@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Lipkin linkage]]></video:title>
      <video:description><![CDATA[Since James Watt invented the steam engine there was a problem of transforming rotary motion of one hinge into the perfect straight-line motion of another. This problem was unsolved for long time. And only beautiful mathematics helped finally to solve it.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/vintage-computers/</loc>
    <lastmod>2007-12-13</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/01@hd.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/01.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/02@hd.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/02.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/04@hd.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/04.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/07@hd.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/07.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_vintage-computers.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/vintage-computers/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Computer engineering in the 1950s]]></video:title>
      <video:description><![CDATA[Machine that immediately does four arithmetical rules itself… Tabulator that prints itself the results of computations…]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/tchebyshev-plantigrade-machine/</loc>
    <lastmod>2007-12-04</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/01@hd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/01.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/02@hd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/02.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/03@hd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/03.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/04@hd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/04.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/05@hd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/05.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/06@hd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/06.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/07@hd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/07.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/08@hd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/08.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/09@hd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/09.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/10@hd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/10.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/TchebRu_plantigrade-machine@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Plantigrade machine]]></video:title>
      <video:description><![CDATA[You think walking cars are a thing of the distant future, from the time of Lucas's Star Wars? Wrong! The world's first such machine was invented in the second half of the 19th century by Russian mathematician P. L. Tchebyshev.]]></video:description>
      <video:duration>175</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/durer-conjecture/</loc>
    <lastmod>2007-06-19</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/01@hd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/01.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/02@hd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/02.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/03@hd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/03.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/04@hd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/04.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/05@hd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/05.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/06@hd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/06.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/07@hd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/07.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/08@hd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/08.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/09@hd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/09.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/10@hd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/10.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/11@hd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/11.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_Durer-conjecture@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/durer-conjecture/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Anti-Durer]]></video:title>
      <video:description><![CDATA[Unsolved problem: Is there exists a convex polyhedron that has only self-intersecting connected nets.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/ray-screening/</loc>
    <lastmod>2007-06-13</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/01@hd.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/01.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/02@hd.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/02.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/03@hd.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/03.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/04@hd.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/04.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/05@hd.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/05.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/06@hd.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/06.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_ray-screening@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/ray-screening/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Screen a ray]]></video:title>
      <video:description><![CDATA[Can we close the propagating in the plane rays with round mirror columns?]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/jacobi-polynomials/</loc>
    <lastmod>2007-06-12</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/01@hd.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/01.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/02@hd.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/02.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/03@hd.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/03.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/04@hd.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/04.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_Jacobi-polynomials@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Nice construction]]></video:title>
      <video:description><![CDATA[Consider several electric charges inside a segment. How will they be arranged to minimize potential energy of the system? It turns out that the charges stopped exactly in the zeros of the Jacobi polynomial.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/corner-reflector/</loc>
    <lastmod>2007-05-13</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Cat’s eye]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/01@hd.jpg</image:loc>
      <image:title><![CDATA[Cat’s eye]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/01.jpg</image:loc>
      <image:title><![CDATA[Cat’s eye]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Mirrors]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/02@hd.jpg</image:loc>
      <image:title><![CDATA[Mirrors]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/02.jpg</image:loc>
      <image:title><![CDATA[Mirrors]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Mirrors]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/03@hd.jpg</image:loc>
      <image:title><![CDATA[Mirrors]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/03.jpg</image:loc>
      <image:title><![CDATA[Mirrors]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/04@hd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/04.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/05@hd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/05.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/06@hd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/06.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Lunohod]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/07@hd.jpg</image:loc>
      <image:title><![CDATA[Lunohod]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/07.jpg</image:loc>
      <image:title><![CDATA[Lunohod]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Lunohod]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/08@hd.jpg</image:loc>
      <image:title><![CDATA[Lunohod]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/08.jpg</image:loc>
      <image:title><![CDATA[Lunohod]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Lunohod]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/09@hd.jpg</image:loc>
      <image:title><![CDATA[Lunohod]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/corner-reflector/09.jpg</image:loc>
      <image:title><![CDATA[Lunohod]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_corner-reflector@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/corner-reflector/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Corner reflector]]></video:title>
      <video:description><![CDATA[Do bicycle and Lunokhod have something in common? Why do the cat’s eye could be only seen by someone who lighten it?]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/geodesic/</loc>
    <lastmod>2007-05-11</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/01@hd.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/01.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/02@hd.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/02.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/03@hd.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/03.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/04@hd.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/04.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/05@hd.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/05.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/06@hd.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geodesic/06.jpg</image:loc>
      <image:title><![CDATA[Shortest path]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_geodesic@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/geodesic/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Shortest path]]></video:title>
      <video:description><![CDATA[On the way from Moscow to Vladivostok planes goes far to the top of the map. Why do they make such a detour while one could go straight forward?]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/drilling-square-holes/</loc>
    <lastmod>2007-02-05</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/01@hd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/01.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/02@hd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/02.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/03@hd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/03.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/04@hd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/04.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/05@hd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/05.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/06@hd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/06.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/07@hd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/07.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/08@hd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/08.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/09@hd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/09.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/10@hd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/10.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/11@hd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/11.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/12@hd.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/12.jpg</image:loc>
      <image:title><![CDATA[Drilling square holes]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_drilling-square-holes@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/drilling-square-holes/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Drilling square holes]]></video:title>
      <video:description><![CDATA[How to perforate a square hole? You just need a special drill.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/polyhedra-development/</loc>
    <lastmod>2006-12-09</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/01@fhd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/01@hd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/01.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/02@fhd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/02@hd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/02.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/03@fhd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/03@hd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/03.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/04@fhd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/04@hd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/04.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/05@fhd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/05@hd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/05.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/06@fhd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/06@hd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/06.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/07@fhd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/07@hd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/07.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/08@fhd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/08@hd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/08.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/09@fhd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/09@hd.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-development/09.jpg</image:loc>
      <image:title><![CDATA[And this is a net?!]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_polyhedra-development@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/polyhedra-development/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[And this is a net?!]]></video:title>
      <video:description><![CDATA[There is a whole variety of nets for the most usual polyhedra.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/cycloid/</loc>
    <lastmod>2006-11-21</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/01@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/01.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/02@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/02.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/03@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/03.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/04@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/04.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/05@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/05.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/06@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/06.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/07@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/07.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/08@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/08.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/09@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/09.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/10@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/10.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/11@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/11.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/12@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/12.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/13@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/13@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/13.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/14@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/14@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/14.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/15@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/15@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/15.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/16@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/16@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/16.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/17@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/17@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/17.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/18@fhd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/18@hd.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/cycloid/18.jpg</image:loc>
      <image:title><![CDATA[Cycloid]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_cycloid@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/cycloid/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Cycloid]]></video:title>
      <video:description><![CDATA[A stone got stuck in the wheel tread. In what direction will it fly when it leaves the tread?]]></video:description>
      <video:duration>147</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/ellipse/</loc>
    <lastmod>2006-11-16</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ellipse/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Ellipse]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ellipse/01@hd.jpg</image:loc>
      <image:title><![CDATA[Ellipse]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ellipse/01.jpg</image:loc>
      <image:title><![CDATA[Ellipse]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ellipse/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Ellipse]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ellipse/02@hd.jpg</image:loc>
      <image:title><![CDATA[Ellipse]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ellipse/02.jpg</image:loc>
      <image:title><![CDATA[Ellipse]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ellipse/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Ellipse]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ellipse/03@hd.jpg</image:loc>
      <image:title><![CDATA[Ellipse]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ellipse/03.jpg</image:loc>
      <image:title><![CDATA[Ellipse]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_ellipse@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/ellipse/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Ellipse]]></video:title>
      <video:description><![CDATA[Draw an ellipse using string and two nails.]]></video:description>
      <video:duration>99</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/polyhedra-net/</loc>
    <lastmod>2006-10-04</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/01@fhd.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/01@hd.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/01.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/02@fhd.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/02@hd.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/02.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/03@fhd.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/03@hd.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/03.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/04@fhd.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/04@hd.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/04.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/05@fhd.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/05@hd.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/05.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/06@fhd.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/06@hd.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-net/06.jpg</image:loc>
      <image:title><![CDATA[The net]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_polyhedra-net@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/polyhedra-net/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[The net]]></video:title>
      <video:description><![CDATA[What is the net of a polyhedron you may ask. It is simply a sheet of cardboard whose folding gives the polyhedron. This is true, but there’s more. The concept of the net of a polyhedron contains something more than just a sheet of cardboard.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/parabolic-antenna/</loc>
    <lastmod>2006-05-27</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/01@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/01.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/02@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/02.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/03@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/03.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/04@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/04.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/05@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/05.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/06@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/06.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/07@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/07.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/08@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/08.jpg</image:loc>
      <image:title><![CDATA[Parabolic antenna]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_parabolic-antenna@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/parabolic-antenna/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Parabolic antenna]]></video:title>
      <video:description><![CDATA[Why do the majority of parabolic antennas resemble each other? To find the answer just remember school mathematics.]]></video:description>
      <video:duration>159</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/magnitsky/</loc>
    <lastmod>2006-05-26</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/01@hd.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/01.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/02@hd.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/02.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/03@hd.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/03.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/04@hd.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/04.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/05_1@fhd.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/05_1@hd.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/05_1.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/05_2@fhd.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/05_2@hd.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/magnitsky/05_2.jpg</image:loc>
      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_Magnitsky.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/magnitsky/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Arithmetic by Magnitsky]]></video:title>
      <video:description><![CDATA[In 1703, Peter the Great organised the publication of the first Russian mathematics textbook. The "Arithmetic" of Leonty Philippovich Magnitsky is published. And during the Great Northern War the tsar edits a geometry textbook himself...]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/cubic-parquet/</loc>
    <lastmod>2006-03-21</lastmod>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_cubic-parquet@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/cubic-parquet/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Cubist parquet]]></video:title>
      <video:description><![CDATA[How many distinct cube nets exist? It’s interesting that any of them can be used to parquet your room.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/polyhedra-embedding/</loc>
    <lastmod>2006-01-24</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/01@hd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/01.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/02@hd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/02.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/03@hd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/03.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/04@hd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/04.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/05@hd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/05.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/06@hd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/06.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/07@hd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/07.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/08@hd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/08.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/09@hd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/09.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/10@hd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/10.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/11@hd.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/11.jpg</image:loc>
      <image:title><![CDATA[Piecewise linear embedding of a polyhedron]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_polyhedra-embedding@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/polyhedra-embedding/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Piecewise linear embedding of a polyhedron]]></video:title>
      <video:description><![CDATA[Can one fold a development of a polyhedron into a closed body, whose borders will be not parts of planes but rather pieces of smooth surfaces?]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/figures-area/</loc>
    <lastmod>2006-01-09</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/01@hd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/01.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/02@hd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/02.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/03@hd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/03.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/04@hd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/04.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/05@hd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/05.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/06@hd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/06.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/07@hd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/07.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/08@hd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/08.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/09@hd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/09.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/10@hd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/10.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/11@hd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/11.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/12@hd.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/figures-area/12.jpg</image:loc>
      <image:title><![CDATA[Plane areas]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_figures-area@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/figures-area/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Plane areas]]></video:title>
      <video:description><![CDATA[The area of a square equals to the square of it’s side length. It’s easy to compute the area of a figure that is built of several squares. And what is the area of a figure bounded by an arbitrary curve?]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/fold-cut-problem/</loc>
    <lastmod>2005-11-16</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/01@fhd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/01@hd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/01.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/02@fhd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/02@hd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/02.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/03@fhd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/03@hd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/03.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/04@fhd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/04@hd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/04.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/05@fhd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/05@hd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/05.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/06@fhd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/06@hd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/06.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/07@fhd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/07@hd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/07.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/08@fhd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/08@hd.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/08.jpg</image:loc>
      <image:title><![CDATA[With a single cut]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_fold-cut-problem@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/fold-cut-problem/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[With a single cut]]></video:title>
      <video:description><![CDATA[Let’s take a sheet of paper and draw an arbitrary polygon. Is it possible to fold the sheet so that the polygon could be cut out with a single straight slit?]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/reuleaux-triangle/</loc>
    <lastmod>2005-03-29</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/01@hd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/01.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/02@hd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/02.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/03@hd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/03.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/04@hd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/04.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/05@hd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/05.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/06.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/17@hd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/17.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/18@hd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/18.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/19@hd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/19.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/20@fhd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/20@hd.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/reuleaux-triangle/20.jpg</image:loc>
      <image:title><![CDATA[Circular Reuleaux triangle]]></image:title>
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      <video:title><![CDATA[Circular Reuleaux triangle]]></video:title>
      <video:description><![CDATA[Let’s consider a regular triangle. On each side of the triangle we’ll draw an arc of a circle of radius equal to the length of the side. Received curve is called ”Reuleaux” triangle.]]></video:description>
      <video:duration>377</video:duration>
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      <video:description><![CDATA[Two cars — loader and tractor — build ladder that goes to infinity. Plunged into their work they prove divergence of the harmonic series.]]></video:description>
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      <video:description><![CDATA[Is it possible to construct both a nonconvex and a convex polyhedra from the same set of faces? You’d definitely say Yes. Which of them has the greater volume?]]></video:description>
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      <video:description><![CDATA[Is it possible to fold a piece of pasteboard of which a milk package is made into a package of greater volume?]]></video:description>
      <video:duration>377</video:duration>
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      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/11.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/12@hd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/12.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/13@fhd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/13@hd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/13.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/14@fhd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/14@hd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/14.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/15@fhd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/15@hd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/15.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/16@fhd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/16@hd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/16.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/17@fhd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/17@hd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/17.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/18@fhd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/18@hd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/18.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/19@fhd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/19@hd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/19.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/20@fhd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/20@hd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/20.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/21@fhd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/21@hd.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/contact-number/21.jpg</image:loc>
      <image:title><![CDATA[Contact number]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_contact-number@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/etudes/contact-number/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Contact number]]></video:title>
      <video:description><![CDATA[In reading this text or in downloading a film you may have used the solution of the balls contact number problem in 8-dimensional space. Are you surprised? This movie tells about applications of this well-known mathematical problem.]]></video:description>
      <video:duration>377</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/etudes/</loc>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parallelogram/thumb.jpg</image:loc>
      <image:title><![CDATA[Parallelogram]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/parallelogram/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Parallelogram]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/pythagorean-theorem-windmill-proof/thumb.jpg</image:loc>
      <image:title><![CDATA[Pythagorean Theorem: Euclid's proof]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/pythagorean-theorem-windmill-proof/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Pythagorean Theorem: Euclid's proof]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-chess/thumb.jpg</image:loc>
      <image:title><![CDATA[Geometric progression: the chess legend]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-chess/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Geometric progression: the chess legend]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/thumb.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/snell/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Snell’s Law]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/thumb.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/kaleidoscope/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Kaleidoscope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/thumb.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/helix/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Helix]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/thumb.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/rainbow/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Rainbow]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/thumb.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/archimedes/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Sphere volume: Archimedes Scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/thumb.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/geometric-progression-gears/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Geometric progression decrease]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/thumb.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/platonic-solids-harmony/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Regular polyhedra harmony]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/thumb.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shukhov-tower/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Shukhov Tower]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/thumb.jpg</image:loc>
      <image:title><![CDATA[Train wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/train-wheelset/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Train wheels]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/thumb.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/invisible-body/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Invisible body]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/windscreen-wiper/thumb.jpg</image:loc>
      <image:title><![CDATA[Hinge mechanisms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/windscreen-wiper/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Hinge mechanisms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/thumb.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/napkin-folding-problem/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Folded rouble]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ham-sandwich-theorem/thumb.jpg</image:loc>
      <image:title><![CDATA[Sandwich problem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ham-sandwich-theorem/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Sandwich problem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/continuity/thumb.jpg</image:loc>
      <image:title><![CDATA[Continuity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/continuity/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Continuity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vernier/thumb.jpg</image:loc>
      <image:title><![CDATA[Vernier scale]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vernier/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Vernier scale]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/pick-theorem/thumb.jpg</image:loc>
      <image:title><![CDATA[Pick’s formula]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/pick-theorem/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Pick’s formula]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/thumb.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-wheelchair/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Wheelchair]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/pythagorean-theorem/thumb.jpg</image:loc>
      <image:title><![CDATA[Pythagorean theorem: Interactive puzzle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/pythagorean-theorem/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Pythagorean theorem: Interactive puzzle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/thumb.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/wheel-inventing/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Inventing the wheel]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/thumb.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/catenary/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Catenary]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/thumb.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/steering-geometry/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Steering geometry]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/flexible-polyhedra/thumb.jpg</image:loc>
      <image:title><![CDATA[Flexible polyhedra]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/flexible-polyhedra/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Flexible polyhedra]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/monge-theorem/thumb.jpg</image:loc>
      <image:title><![CDATA[Leaving the plane]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/monge-theorem/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Leaving the plane]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/thumb.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ball-volume/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Ball volume]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/thumb.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/shadows/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Shadows]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/thumb.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/axioms/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Axioms]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/thumb.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-sorting-mechanism/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Sorting mechanism]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/thumb.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/translation-rotation/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Translation and rotation]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/thumb.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/underground/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[How deep is the underground station]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/thumb.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/angle-trisection/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Angle trisection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/thumb.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/degrees-of-freedom/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Degrees of freedom]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/thumb.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/lipkin-inversor/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Lipkin linkage]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/thumb.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/vintage-computers/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Computer engineering in the 1950s]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/thumb.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/tchebyshev-plantigrade-machine/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Plantigrade machine]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/thumb.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/durer-conjecture/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Anti-Durer]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/ray-screening/thumb.jpg</image:loc>
      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Screen a ray]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Nice construction]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/etudes/jacobi-polynomials/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Nice construction]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Corner reflector]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Corner reflector]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Shortest path]]></image:title>
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    <image:image>
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    <image:image>
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    <image:image>
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      <image:title><![CDATA[Drilling square holes]]></image:title>
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    <image:image>
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    <image:image>
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    <image:image>
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    <image:image>
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    <image:image>
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      <image:title><![CDATA[Ellipse]]></image:title>
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    <image:image>
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    <image:image>
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    <image:image>
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      <image:title><![CDATA[Parabolic antenna]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Parabolic antenna]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Arithmetic by Magnitsky]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Number cubes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-cubes/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Number cubes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-cubes/06@hd.jpg</image:loc>
      <image:title><![CDATA[Number cubes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-cubes/06.jpg</image:loc>
      <image:title><![CDATA[Number cubes]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-cubes/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Number cubes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-cubes/07@hd.jpg</image:loc>
      <image:title><![CDATA[Number cubes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-cubes/07.jpg</image:loc>
      <image:title><![CDATA[Number cubes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-cubes/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Number cubes]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-cubes/08@hd.jpg</image:loc>
      <image:title><![CDATA[Number cubes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-cubes/08.jpg</image:loc>
      <image:title><![CDATA[Number cubes]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Number cubes]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Number cubes]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-cubes/09.jpg</image:loc>
      <image:title><![CDATA[Number cubes]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/01@hd.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/01.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/02@hd.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/02.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/03@hd.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/03.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/04@hd.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/04.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/05@hd.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/05.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/06@hd.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/cube-capacity/06.jpg</image:loc>
      <image:title><![CDATA[Cube capacity]]></image:title>
    </image:image>
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      <video:title><![CDATA[Cube capacity]]></video:title>
      <video:description><![CDATA[How big tetrahedron can fit into a cube?]]></video:description>
      <video:duration>137</video:duration>
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    <lastmod>2021-01-12</lastmod>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/pythagorean-theorem-sand-proof/01.jpg</image:loc>
      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/pythagorean-theorem-sand-proof/02@hd.jpg</image:loc>
      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
    <image:image>
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    </image:image>
    <image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
    <image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
    </image:image>
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      <video:description><![CDATA[Illustration and proofs of Pythagorean theorem.]]></video:description>
      <video:duration>53</video:duration>
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    <loc>https://en.etudes.ru/models/binary-magic/</loc>
    <lastmod>2021-01-05</lastmod>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/stereographic-projection/05@hd.jpg</image:loc>
      <image:title><![CDATA[Stereographic projection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/stereographic-projection/05.jpg</image:loc>
      <image:title><![CDATA[Stereographic projection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/stereographic-projection/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Stereographic projection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/stereographic-projection/06@hd.jpg</image:loc>
      <image:title><![CDATA[Stereographic projection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/stereographic-projection/06.jpg</image:loc>
      <image:title><![CDATA[Stereographic projection]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_stereographic-projection@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/stereographic-projection/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Stereographic projection]]></video:title>
      <video:description><![CDATA[Rectangular grid as the shadow of a spherical model.]]></video:description>
      <video:duration>115</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/geometric-progression-sum/</loc>
    <lastmod>2020-12-08</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/geometric-progression-sum/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Sum of an infinite geometric progression]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/geometric-progression-sum/01@hd.jpg</image:loc>
      <image:title><![CDATA[Sum of an infinite geometric progression]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/geometric-progression-sum/01.jpg</image:loc>
      <image:title><![CDATA[Sum of an infinite geometric progression]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/geometric-progression-sum/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Sum of an infinite geometric progression]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/geometric-progression-sum/02@hd.jpg</image:loc>
      <image:title><![CDATA[Sum of an infinite geometric progression]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/geometric-progression-sum/02.jpg</image:loc>
      <image:title><![CDATA[Sum of an infinite geometric progression]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/geometric-progression-sum/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Sum of an infinite geometric progression]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/geometric-progression-sum/03@hd.jpg</image:loc>
      <image:title><![CDATA[Sum of an infinite geometric progression]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/geometric-progression-sum/03.jpg</image:loc>
      <image:title><![CDATA[Sum of an infinite geometric progression]]></image:title>
    </image:image>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/conic-sections-hyperbola-surface-tension/</loc>
    <lastmod>2020-12-01</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/01@hd.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/01.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/02@hd.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/02.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/03@hd.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/03.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/04@hd.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/04.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/05@hd.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/05.jpg</image:loc>
      <image:title><![CDATA[Hyperbole: the surface tension of water]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_conic-sections_hyperbola-surface-tension@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/conic-sections-hyperbola-surface-tension/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Hyperbole: the surface tension of water]]></video:title>
      <video:description><![CDATA[Hyperbola at home can be "drawn" by surface tension forces.]]></video:description>
      <video:duration>48</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/sine-wave/</loc>
    <lastmod>2020-11-24</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/01@hd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/01.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/02@hd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/02.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/03@hd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/03.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/04@hd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/04.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/05@hd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/05.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/06@hd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/06.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/07@hd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/07.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/08@hd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/08.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/09@hd.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sine-wave/09.jpg</image:loc>
      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_sine-wave-sausage@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/sine-wave/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Sine wave: cylinder net]]></video:title>
      <video:description><![CDATA[The sine graph can be obtained as a "sliced off" cylinder (or with an ellipse drawn on it)]]></video:description>
      <video:duration>45</video:duration>
    </video:video>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_sine-wave-cylinder-development@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/sine-wave/poster-sine-wave-cylinder-development@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Sine wave: cylinder net]]></video:title>
      <video:description><![CDATA[The sine graph can be obtained as a "sliced off" cylinder (or with an ellipse drawn on it)]]></video:description>
      <video:duration>29</video:duration>
    </video:video>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_sine-wave-cylinder-rolling@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/sine-wave/poster-sine-wave-cylinder-rolling@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Sine wave: cylinder net]]></video:title>
      <video:description><![CDATA[The sine graph can be obtained as a "sliced off" cylinder (or with an ellipse drawn on it)]]></video:description>
      <video:duration>31</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/corner-reflector/</loc>
    <lastmod>2020-11-17</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/corner-reflector/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/corner-reflector/01@hd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/corner-reflector/01.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/corner-reflector/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/corner-reflector/02@hd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/corner-reflector/02.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/corner-reflector/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/corner-reflector/03@hd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/corner-reflector/03.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/corner-reflector/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/corner-reflector/04@hd.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/corner-reflector/04.jpg</image:loc>
      <image:title><![CDATA[Corner reflector]]></image:title>
    </image:image>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/conic-sections-confocal-ellipses/</loc>
    <lastmod>2020-11-10</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-confocal-ellipses/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Grave’s confocal ellipses]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-confocal-ellipses/01@hd.jpg</image:loc>
      <image:title><![CDATA[Grave’s confocal ellipses]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-confocal-ellipses/01.jpg</image:loc>
      <image:title><![CDATA[Grave’s confocal ellipses]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-confocal-ellipses/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Grave’s confocal ellipses]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-confocal-ellipses/02@hd.jpg</image:loc>
      <image:title><![CDATA[Grave’s confocal ellipses]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-confocal-ellipses/02.jpg</image:loc>
      <image:title><![CDATA[Grave’s confocal ellipses]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-confocal-ellipses/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Grave’s confocal ellipses]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-confocal-ellipses/03@hd.jpg</image:loc>
      <image:title><![CDATA[Grave’s confocal ellipses]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-confocal-ellipses/03.jpg</image:loc>
      <image:title><![CDATA[Grave’s confocal ellipses]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_conic-sections_confocal-ellipses@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/conic-sections-confocal-ellipses/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Grave’s confocal ellipses]]></video:title>
      <video:description><![CDATA[Whenever you move from a circle to an ellipse, elementary statements arise that have no elementary proof.]]></video:description>
      <video:duration>80</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/conic-sections-hyperbolic-paraboloid-carboard-model/</loc>
    <lastmod>2020-11-03</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbolic-paraboloid-carboard-model/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Hyperbolic paraboloid: a cardboard model]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbolic-paraboloid-carboard-model/01@hd.jpg</image:loc>
      <image:title><![CDATA[Hyperbolic paraboloid: a cardboard model]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-hyperbolic-paraboloid-carboard-model/01.jpg</image:loc>
      <image:title><![CDATA[Hyperbolic paraboloid: a cardboard model]]></image:title>
    </image:image>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/lobachevskian-plane-models/</loc>
    <lastmod>2020-10-27</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/01@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/01.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/02@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/02.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/03@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/03.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/04@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/04.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/05@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/05.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/06@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/06.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/07@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/07.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/08@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/08.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/09@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/09.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/10@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/10.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/11@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/11.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/12@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/12.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/13@fhd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/13@hd.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/13.jpg</image:loc>
      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_Lobachevskian-plane-models@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/lobachevskian-plane-models/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Three Lobachevskian plane models]]></video:title>
      <video:description><![CDATA[A transparent hemisphere with marked circles perpendicular to the equator delivers three models of the Lobachevsky plane at once.]]></video:description>
      <video:duration>98</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/conic-sections-moire/</loc>
    <lastmod>2020-02-07</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-moire/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Conic sections: moiré]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-moire/01@hd.jpg</image:loc>
      <image:title><![CDATA[Conic sections: moiré]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-moire/01.jpg</image:loc>
      <image:title><![CDATA[Conic sections: moiré]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-moire/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Conic sections: moiré]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-moire/02@hd.jpg</image:loc>
      <image:title><![CDATA[Conic sections: moiré]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-moire/02.jpg</image:loc>
      <image:title><![CDATA[Conic sections: moiré]]></image:title>
    </image:image>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/dihedral-group/</loc>
    <lastmod>2018-12-24</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/01@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/01.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/02@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/02.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/03@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/03.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/04@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/04.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/05@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/05.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/06@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/06.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/07@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/07.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/08@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/08.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/09@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/09.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/10@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/10.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/11@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/11@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/11.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/12@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/12@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/12.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/13@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/13@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/13.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/14@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/14@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/14.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/15@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/15@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/15.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/16@fhd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/16@hd.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dihedral-group/16.jpg</image:loc>
      <image:title><![CDATA[Dihedral group]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_dihedral-group@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/dihedral-group/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Dihedral group]]></video:title>
      <video:description><![CDATA[A mirror angle is a simplest kaleidoscope that produces regular polygons.]]></video:description>
      <video:duration>98</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/conic-sections-parabola-reflective-property/</loc>
    <lastmod>2018-12-09</lastmod>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_conic-sections_parabolic-plate@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/conic-sections-parabola-reflective-property/poster-conic-sections_parabolic-plate@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Parabola: optical property]]></video:title>
      <video:description><![CDATA[The optical property of the parabola is the basis of the parabola's many applications in our life.]]></video:description>
      <video:duration>27</video:duration>
    </video:video>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_conic-sections_parabolic-lighter@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/conic-sections-parabola-reflective-property/poster-conic-sections_parabolic-lighter@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Parabola: optical property]]></video:title>
      <video:description><![CDATA[The optical property of the parabola is the basis of the parabola's many applications in our life.]]></video:description>
      <video:duration>24</video:duration>
    </video:video>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_conic-sections_parabolic-mirrors@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/conic-sections-parabola-reflective-property/poster-conic-sections_parabolic-mirrors@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Parabola: optical property]]></video:title>
      <video:description><![CDATA[The optical property of the parabola is the basis of the parabola's many applications in our life.]]></video:description>
      <video:duration>23</video:duration>
    </video:video>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_conic-sections_parabolic-kitchen@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/conic-sections-parabola-reflective-property/poster-conic-sections_parabolic-kitchen@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Parabola: optical property]]></video:title>
      <video:description><![CDATA[The optical property of the parabola is the basis of the parabola's many applications in our life.]]></video:description>
      <video:duration>33</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/conic-sections-parabolic-billiard/</loc>
    <lastmod>2018-12-05</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/01@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/01.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/02@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/02.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/03@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/03.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/04@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/04.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/05@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/05.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/06@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/06.jpg</image:loc>
      <image:title><![CDATA[Parabolic billiard]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_conic-sections_parabolic-billiard@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/conic-sections-parabolic-billiard/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Parabolic billiard]]></video:title>
      <video:description><![CDATA[A ball rolling down the slide in a parabolic billiard always makes it to the pocket!]]></video:description>
      <video:duration>54</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/football-mirror-icosahedron/</loc>
    <lastmod>2018-06-13</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/01@hd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/01.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/02@hd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/02.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/03@hd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/03.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/04@hd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/04.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/05@hd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/05.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/06@hd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/06.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/07@hd.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/07.jpg</image:loc>
      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_football-mirror-icosahedron@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/football-mirror-icosahedron/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Football: mirror icosahedron]]></video:title>
      <video:description><![CDATA[Three triangular mirrors, some duct tape and a triangle painted in two colors, combined with the theory of reflection groups allow you to demonstrate an interesting model of a classic soccer ball to your friends.]]></video:description>
      <video:duration>62</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/conic-sections-chips-hyperbolic-paraboloid/</loc>
    <lastmod>2018-06-05</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/01@hd.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/01.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/02@hd.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/02.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/03@hd.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/03.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/04@hd.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/04.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/05@hd.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/05.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/06@hd.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/06.jpg</image:loc>
      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_conic-sections_chips-hyperbolic-paraboloid@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/conic-sections-chips-hyperbolic-paraboloid/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Chips: hyperbolic paraboloid]]></video:title>
      <video:description><![CDATA[Сhips, packed in a cylindric tube, have a shape of a hyperbolic paraboloid, so they can pass through a narrow hole without breaking!]]></video:description>
      <video:duration>78</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/conic-sections-sadle-hyperbolic-paraboloid/</loc>
    <lastmod>2018-03-29</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/01@hd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/01.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/02@hd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/02.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/03@hd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/03.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/04@hd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/04.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/05@hd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/05.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/06@hd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/06.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/07@hd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/07.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/08@hd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/08.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/09@hd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/09.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/10@hd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/10.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_conic-sections_sadle-hyperbolic-paraboloid@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></video:title>
      <video:description><![CDATA[A surface of a hyperbolic paraboloid looks like a saddle, but it can be formed by a movement of a straight line.]]></video:description>
      <video:duration>149</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/number-pi/</loc>
    <lastmod>2018-03-14</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/01@hd.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/01.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/02@hd.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/02.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/03@hd.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/03.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/04@hd.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/04.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_number-pi@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/number-pi/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Number π]]></video:title>
      <video:description><![CDATA[A simple to do demonstration that the number π equals “three and change”.]]></video:description>
      <video:duration>64</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/educated-monkey/</loc>
    <lastmod>2018-02-15</lastmod>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/conic-sections-parabola-geometric-definition/</loc>
    <lastmod>2017-09-02</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/01@hd.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/01.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/02@hd.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/02.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/03@hd.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/03.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/04@hd.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/04.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_conic-sections_parabola-geometric-definition@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Plotting a parabola. Geometric definition]]></video:title>
      <video:description><![CDATA[Drawing a parabola with a thread according to its geometric definition.]]></video:description>
      <video:duration>46</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/conic-sections-cavalieri-parabolograf/</loc>
    <lastmod>2017-09-01</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/01@hd.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/01.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/02@hd.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/02.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/03@hd.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/03.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/04@hd.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/04.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/05@hd.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/05.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_conic-sections_Cavalieri-parabolograf@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Cavalieri’s parabolograph]]></video:title>
      <video:description><![CDATA[A XVII century tool for drawing parabola, whose functioning is based on a theorem from a modern school mathematics course.]]></video:description>
      <video:duration>81</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/trapezium-area/</loc>
    <lastmod>2014-06-02</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/01@hd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/01.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/02@hd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/02.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/03@hd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/03.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/04@hd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/04.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/05@hd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/05.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/06@hd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/06.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/07@hd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/07.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/08@hd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/08.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_area-trapezium-to-rectangle@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/trapezium-area/poster-area-trapezium-to-rectangle@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Trapezoid area]]></video:title>
      <video:description><![CDATA[Trapezoid area is equal to half the product of the height and the sum of the two bases.]]></video:description>
      <video:duration>36</video:duration>
    </video:video>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_area-trapezium-to-triangle@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/trapezium-area/poster-area-trapezium-to-triangle@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Trapezoid area]]></video:title>
      <video:description><![CDATA[Trapezoid area is equal to half the product of the height and the sum of the two bases.]]></video:description>
      <video:duration>33</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/dudeney-dissection/</loc>
    <lastmod>2014-06-01</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/01@hd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/01.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/02@hd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/02.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/03@hd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/03.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/04@hd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/04.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/05@hd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/05.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/06@hd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/06.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_Dudeney-dissection@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/dudeney-dissection/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Dudeny dissection]]></video:title>
      <video:description><![CDATA[What is the minimal number of parts an equilateral triangle should be cut into so that a square can be formed rearranging them?]]></video:description>
      <video:duration>76</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/volume-balance/</loc>
    <lastmod>2013-10-26</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/01@hd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/01.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/02@hd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/02.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/03@hd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/03.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/04@hd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/04.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/05@hd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/05.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/06@hd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/06.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
    </image:image>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/chasles-theorem/</loc>
    <lastmod>2013-10-25</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/01@hd.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/01.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/02@hd.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/02.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/03@hd.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/03.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/04@hd.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/04.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/05@hd.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/05.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
    </image:image>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/conic-sections-water/</loc>
    <lastmod>2013-02-19</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/01@hd.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/01.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/02@hd.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/02.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/03@hd.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/03.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/04@hd.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/04.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/05@hd.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/05.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_conic-sections_water@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/conic-sections-water/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Conic sections. A cone with water]]></video:title>
      <video:description><![CDATA[All the conic sections — an ellipse, a parabola and a hyperbola — can be seen on water surface.]]></video:description>
      <video:duration>50</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/exterior-angles-sum/</loc>
    <lastmod>2013-02-17</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/01@hd.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/01.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/02@hd.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/02.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/03@hd.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/03.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/04@hd.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/04.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/05@hd.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/05.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_exterior-angles-sum@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/exterior-angles-sum/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Exterior angles sum of a convex polygon]]></video:title>
      <video:description><![CDATA[The sum of exterior angles of a convex polygon is 360°.]]></video:description>
      <video:duration>62</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/sum-of-squares/</loc>
    <lastmod>2013-02-17</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/01@hd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/01.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/02@hd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/02.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/03@hd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/03.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/04@hd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/04.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/05@hd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/05.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/06@hd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/06.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
    </image:image>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_sum-of-squares@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/sum-of-squares/poster-wooden@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Sum of squares]]></video:title>
      <video:description><![CDATA[What’s the sum of squares of first n natural numbers?]]></video:description>
      <video:duration>97</video:duration>
    </video:video>
    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_sum-of-squares_colour@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/sum-of-squares/thumb@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Sum of squares]]></video:title>
      <video:description><![CDATA[What’s the sum of squares of first n natural numbers?]]></video:description>
      <video:duration>106</video:duration>
    </video:video>
  </url>
  <url>
    <loc>https://en.etudes.ru/models/circle-area/</loc>
    <lastmod>2013-02-15</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/01@hd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/01.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/02@fhd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/02@hd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/02.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/03@hd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/03.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/04@fhd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/04@hd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/04.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/05@fhd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/05@hd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/05.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/06@fhd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/06@hd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/06.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/07@fhd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/07@hd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/07.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/08@fhd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/08@hd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/08.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/09@fhd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/09@hd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/09.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/10@fhd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/10@hd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/10.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
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      <video:title><![CDATA[Circle area]]></video:title>
      <video:description><![CDATA[Calculating the area of a circle using area formulas for a rectangle and a triangle.]]></video:description>
      <video:duration>46</video:duration>
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    <video:video>
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      <video:title><![CDATA[Circle area]]></video:title>
      <video:description><![CDATA[Calculating the area of a circle using area formulas for a rectangle and a triangle.]]></video:description>
      <video:duration>49</video:duration>
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    <loc>https://en.etudes.ru/models/steinhaus-dodecahedron/</loc>
    <lastmod>2013-02-13</lastmod>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/steinhaus-dodecahedron/01@fhd.jpg</image:loc>
      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/steinhaus-dodecahedron/03@fhd.jpg</image:loc>
      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/steinhaus-dodecahedron/05@hd.jpg</image:loc>
      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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      <video:title><![CDATA[Steinhaus Dodecahedron]]></video:title>
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      <video:title><![CDATA[Steinhaus Dodecahedron]]></video:title>
      <video:description><![CDATA[A cardboard model of a dodecahedron — one of the five regular polyhedra.]]></video:description>
      <video:duration>59</video:duration>
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    <video:video>
      <video:content_loc>https://en.etudes.ru/.data/video/EtudesRu_models_Steinhaus-dodecahedron-Adygea@fhd.mp4</video:content_loc>
      <video:thumbnail_loc>https://en.etudes.ru/.data/models/steinhaus-dodecahedron/poster-Steinhaus-dodecahedron-Adygea@fhd.jpg</video:thumbnail_loc>
      <video:title><![CDATA[Steinhaus Dodecahedron]]></video:title>
      <video:description><![CDATA[A cardboard model of a dodecahedron — one of the five regular polyhedra.]]></video:description>
      <video:duration>41</video:duration>
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      <image:title><![CDATA[ENENENEN]]></image:title>
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      <image:title><![CDATA[ENENENEN]]></image:title>
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      <image:title><![CDATA[Harmonic series]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Harmonic series]]></image:title>
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      <image:title><![CDATA[Hyperboloid generatix rotation]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Hyperboloid generatix rotation]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Number cubes]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Number cubes]]></image:title>
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      <image:title><![CDATA[Cube capacity]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Cube capacity]]></image:title>
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      <image:title><![CDATA[Pythagorean Theorem: illustration with sand]]></image:title>
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    <image:image>
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    <image:image>
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      <image:title><![CDATA[Binary magic]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/binary-magic/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Binary magic]]></image:title>
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      <image:title><![CDATA[Vanishing cell and the Fibonacci numbers]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Stereographic projection]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Stereographic projection]]></image:title>
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      <image:title><![CDATA[Sum of an infinite geometric progression]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Sine wave: cylinder net]]></image:title>
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      <image:title><![CDATA[Corner reflector]]></image:title>
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      <image:title><![CDATA[Corner reflector]]></image:title>
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      <image:title><![CDATA[Hyperbolic paraboloid: a cardboard model]]></image:title>
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      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
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      <image:title><![CDATA[Three Lobachevskian plane models]]></image:title>
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      <image:title><![CDATA[Conic sections: moiré]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Conic sections: moiré]]></image:title>
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      <image:title><![CDATA[Dihedral group]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Dihedral group]]></image:title>
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      <image:title><![CDATA[Parabola: optical property]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Parabola: optical property]]></image:title>
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      <image:title><![CDATA[Parabolic billiard]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Parabolic billiard]]></image:title>
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      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Football: mirror icosahedron]]></image:title>
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      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
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    <image:image>
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      <image:title><![CDATA[Chips: hyperbolic paraboloid]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-sadle-hyperbolic-paraboloid/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Saddle surface of a hyperbolic paraboloid]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/thumb.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/number-pi/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Number π]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/educated-monkey/thumb.jpg</image:loc>
      <image:title><![CDATA[Consul, The Educated Monkey]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/educated-monkey/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Consul, The Educated Monkey]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/thumb.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-parabola-geometric-definition/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Plotting a parabola. Geometric definition]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/thumb.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-cavalieri-parabolograf/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Cavalieri’s parabolograph]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/thumb.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/trapezium-area/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Trapezoid area]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/thumb.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/dudeney-dissection/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Dudeny dissection]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/thumb.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/volume-balance/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Volumes: Lever scales]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/thumb.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/chasles-theorem/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Chasles’ theorem]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/thumb.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/conic-sections-water/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Conic sections. A cone with water]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/thumb.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/exterior-angles-sum/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Exterior angles sum of a convex polygon]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/thumb.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/sum-of-squares/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Sum of squares]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/thumb.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/circle-area/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Circle area]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/steinhaus-dodecahedron/thumb.jpg</image:loc>
      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/models/steinhaus-dodecahedron/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Steinhaus Dodecahedron]]></image:title>
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    <loc>https://en.etudes.ru/sketches/hilbert-third-problem/</loc>
    <lastmod>2016-05-13</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/parabolic-sieve/</loc>
    <lastmod>2014-03-29</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/szilassi-polyhedron/</loc>
    <lastmod>2013-05-07</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/shortest-path/</loc>
    <lastmod>2012-09-27</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/odd-numbers-sum/</loc>
    <lastmod>2012-06-01</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/pythagorean-triangle/</loc>
    <lastmod>2010-04-12</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/triangle-sum-of-angles/</loc>
    <lastmod>2010-02-26</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/hypocycloid/</loc>
    <lastmod>2008-09-24</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/square-of-sum/</loc>
    <lastmod>2008-09-08</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/reutersvard-impossible-triangle/</loc>
    <lastmod>2008-03-05</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/maze-cube/</loc>
    <lastmod>2008-02-06</lastmod>
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    <loc>https://en.etudes.ru/sketches/billiard-trajectories/</loc>
    <lastmod>2007-05-24</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/prime-numbers/</loc>
    <lastmod>2007-05-23</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/platonic-solids/</loc>
    <lastmod>2007-04-11</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/tetrahedron-altitude/</loc>
    <lastmod>2007-04-10</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/two-circles-paradox/</loc>
    <lastmod>2007-02-02</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/reuleaux-triangle-rotor/</loc>
    <lastmod>2007-02-01</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/polyhedrons-duality/</loc>
    <lastmod>2006-05-25</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/hyperbola-ellipse-perpendicularity/</loc>
    <lastmod>2006-02-07</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/room-illumination/</loc>
    <lastmod>2005-12-09</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/hyperbola-envelope/</loc>
    <lastmod>2005-12-08</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/ellipse-envelope/</loc>
    <lastmod>2005-12-07</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/parabola-envelope/</loc>
    <lastmod>2005-12-06</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/parabola-optic-property/</loc>
    <lastmod>2005-12-05</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/ellipse-optic-property/</loc>
    <lastmod>2005-12-04</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/timber-rafting/</loc>
    <lastmod>2005-12-03</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/astroid/</loc>
    <lastmod>2005-12-02</lastmod>
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  <url>
    <loc>https://en.etudes.ru/sketches/cat-on-ladder/</loc>
    <lastmod>2005-12-01</lastmod>
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  <url>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/hilbert-third-problem/thumb.jpg</image:loc>
      <image:title><![CDATA[Equivalency and equidecomposability]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/hilbert-third-problem/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Equivalency and equidecomposability]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/parabolic-sieve/thumb.jpg</image:loc>
      <image:title><![CDATA[Parabolic sieve]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/parabolic-sieve/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Parabolic sieve]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/szilassi-polyhedron/thumb.jpg</image:loc>
      <image:title><![CDATA[Szilassi polyhedron]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/szilassi-polyhedron/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Szilassi polyhedron]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/shortest-path/thumb.jpg</image:loc>
      <image:title><![CDATA[Walking tours]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/shortest-path/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Walking tours]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/odd-numbers-sum/thumb.jpg</image:loc>
      <image:title><![CDATA[Odd numbers sum]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/odd-numbers-sum/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Odd numbers sum]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/pythagorean-triangle/thumb.jpg</image:loc>
      <image:title><![CDATA[Pythagorean triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/pythagorean-triangle/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Pythagorean triangle]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/triangle-sum-of-angles/thumb.jpg</image:loc>
      <image:title><![CDATA[Triangle interior angles sum]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/triangle-sum-of-angles/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Triangle interior angles sum]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/hypocycloid/thumb.jpg</image:loc>
      <image:title><![CDATA[Hypocycloid]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/hypocycloid/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Hypocycloid]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/square-of-sum/thumb.jpg</image:loc>
      <image:title><![CDATA[Square of a sum]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/square-of-sum/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Square of a sum]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/reutersvard-impossible-triangle/thumb.jpg</image:loc>
      <image:title><![CDATA[Reutersvärd’s Impossible Triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/reutersvard-impossible-triangle/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Reutersvärd’s Impossible Triangle]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/maze-cube/thumb.jpg</image:loc>
      <image:title><![CDATA[Tricky cube]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/maze-cube/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Tricky cube]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/billiard-trajectories/thumb.jpg</image:loc>
      <image:title><![CDATA[Periodic billiard trajectory]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/billiard-trajectories/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Periodic billiard trajectory]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/prime-numbers/thumb.jpg</image:loc>
      <image:title><![CDATA[Are there many prime numbers?]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/prime-numbers/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Are there many prime numbers?]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/platonic-solids/thumb.jpg</image:loc>
      <image:title><![CDATA[Platonic solids]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/platonic-solids/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Platonic solids]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/tetrahedron-altitude/thumb.jpg</image:loc>
      <image:title><![CDATA[Tetrahedron altitudes]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/tetrahedron-altitude/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Tetrahedron altitudes]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/two-circles-paradox/thumb.jpg</image:loc>
      <image:title><![CDATA[Two circles]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/two-circles-paradox/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Two circles]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/reuleaux-triangle-rotor/thumb.jpg</image:loc>
      <image:title><![CDATA[Rotor]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/reuleaux-triangle-rotor/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Rotor]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/polyhedrons-duality/thumb.jpg</image:loc>
      <image:title><![CDATA[Duality of regular polyhedrons]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/polyhedrons-duality/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Duality of regular polyhedrons]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/hyperbola-ellipse-perpendicularity/thumb.jpg</image:loc>
      <image:title><![CDATA[Hyperbola and ellipse perpendicularity]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/hyperbola-ellipse-perpendicularity/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Hyperbola and ellipse perpendicularity]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/room-illumination/thumb.jpg</image:loc>
      <image:title><![CDATA[Room illumination]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/room-illumination/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Room illumination]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/hyperbola-envelope/thumb.jpg</image:loc>
      <image:title><![CDATA[Hyperbola as an envelope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/hyperbola-envelope/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Hyperbola as an envelope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/ellipse-envelope/thumb.jpg</image:loc>
      <image:title><![CDATA[Ellipse as an envelope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/ellipse-envelope/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Ellipse as an envelope]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/parabola-envelope/thumb.jpg</image:loc>
      <image:title><![CDATA[Parabola as an envelope]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/parabola-envelope/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Parabola as an envelope]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/parabola-optic-property/thumb.jpg</image:loc>
      <image:title><![CDATA[Parabola optical property]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/parabola-optic-property/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Parabola optical property]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/ellipse-optic-property/thumb.jpg</image:loc>
      <image:title><![CDATA[Ellipsis optical property]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/ellipse-optic-property/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Ellipsis optical property]]></image:title>
    </image:image>
    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/timber-rafting/thumb.jpg</image:loc>
      <image:title><![CDATA[Timber rafting]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/timber-rafting/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Timber rafting]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/astroid/thumb.jpg</image:loc>
      <image:title><![CDATA[Astroid]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/astroid/thumb@hd.jpg</image:loc>
      <image:title><![CDATA[Astroid]]></image:title>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/cat-on-ladder/thumb.jpg</image:loc>
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    <image:image>
      <image:loc>https://en.etudes.ru/.data/sketches/cat-on-ladder/thumb@hd.jpg</image:loc>
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