Animation of the act of unrolling a circle's circumference, illustrating the ratio <a href="https://en.wikipedia.org/wiki/Pi" class="extiw" title="w:Pi">π</a>. Oversize (720px) and anti-aliased version of <a href="//commons.wikimedia.org/wiki/File:Pi-unrolled.gif" title="File:Pi-unrolled.gif">Image:Pi-unrolled.gif</a> 720×228 (266,713 bytes).
<a href="https://en.wikipedia.org/wiki/User:John_Reid" class="extiw" title="en:User:John Reid">John Reid</a> &amp; <a href="//commons.wikimedia.org/wiki/User:Harp" title="User:Harp">Arpad Horvath</a>
CC BY-SA 3.0
<a href="//commons.wikimedia.org/wiki/File:Pi-unrolled-720.gif" title="File:Pi-unrolled-720.gif">Image:Pi-unrolled-720.gif</a>