Diameter of a <a href="https://en.wikipedia.org/wiki/circle" class="extiw" title="w:circle">circle</a>.
<a href="//commons.wikimedia.org/wiki/User:Krishnavedala" title="User:Krishnavedala">Krishnavedala</a>
2012-01-22
<span class="int-own-work" lang="en">Own work</span>