Van Schooten's Ellipse

A nifty construction of an ellipse by motion of a triangle along two axes. Tumblr post about this: [url]http://mathhombre.tumblr.com/post/65994692165/i-saw-this-great-gif-of-the-van-schooten-ellipse[/url]

More GeoGebra at [url]mathhombre.blogspot.com[/url]