Conic Sections Defined by Eccentricity
Java Sketchpad version (Java
enabled browser required)
Geometer's Sketchpad
version (GSP
4 required) 
Conic Sections Defined by Eccentricity
1. Move the slider for eccentricity and see
what kind of conic section you get.
2. Move the focus to see what impact that has on the figure.
3. Move a point on the directrix to show that no matter what point
is taken on the curve, the ratio of the distance to the focus over
the distance to the directrix always equals the eccentricity.
