1a) use integration in spherical coordinates in order to obtain the general formula for the volume of the ball of radius r.
1b) consider the following two solids: the ball of radius 3 centered at the origin and : the cone defined by the condition φ ≤ π/4 where φ is the spherical coordinate with the same symbol. their intersection looks like an ice-cream cone. use integration with spherical coordinates in order to compute the volume of this intersection.