A right circular cone of base radius r cm and height h cm fits exactly into a sphere of internal radius 12cm.

a)Express r in terms of h.

b)If the volume of the cone is Vcm cube, show that V=8¶h^2 - 1/3¶h^3

c)Find the value of r for which V has a turning value, and determine whether the value of V is a maximum of a minimum. Hence find this volume.

(¶ is Pi, i typed it out, looks weird)

P.S. I know how to determine whether a value is a max of min value, but i'm not sure about other parts to this question! I'd love to know how to do this question!