I got interested in this by Matt Henderson's recent ellipse animation, [url]http://blog.matthen.com/post/5910510944/this-animation-suggests-one-way-to-draw-a-perfect[/url] I liked the idea of the user being able to change the conditions, and also GeoGebra's ability yo show how that changes the ellipse data. What do you notice?
More GeoGebra at [url]mathhombre.blogspot.com[/url]. Any other features to add?