Part of a chapter review problem. Say you have a sphere centered at the origin and of radius 'a'. And you have a (ice-cream) cone which has it's point at the origin and phi equal to ∏/3. How do I find the equation of their intersection? Which is the projection onto the xy plane. Basically, I have to find the volume of the cone given the radius of the sphere (curvature of ice-cream) and phi = ∏/3... My answer needs to be in polar form, so I need to find the region of the projection, which has the same equation as their intersection, where z=0.... Now I'm confusing myself... Any help would be nice. Cheers.