One of the most elegant I've ever seen. Either by him or a tribute to him, so appropriate. First seen at jpedMaths [url]http://jpedmaths.tumblr.com/post/87781743185/this-beautiful-proof-of-the-ancient-theorem-of[/url] A, B, and C are movable.
More GeoGebra at [url]bit.ly/mh-ggb[/url]