Snce the volume of a cube is equal to the length of one side cubed, you need to determine the side length from whatever data you've been govem in spherical coordinates. For example, if the cube is centered on the origin, and you know the value of R from the origin to one of the corners, then from simple geometry the side length is:


L = \sqrt { \frac 4 3 } R


So the volume would be:


V=(\frac 4 3 ) ^{3/2} R