Doubled Spheres

Move the slider for a to manipulate this applet. The following are all based on the variable a: -The radius of the small sphere is a -The radius of the large sphere is 2a -The Volumes and Surface Areas of the spheres are displayed dynamically on the left -Point D is a point (x,y) of (radius, volume) for the small sphere -Point F is a point (x,y) of (radius, surface area) for the small sphere