Part II: (30 points) Solve 3 complete problems out of 5 8. (a) Find the z-coordinate of the center of mass of a solid bounded below by the ry-plane, on the inside by the cone z2 and on the outside by the sphere x2 + y2 + 22-4 and having density δ(x, y, z) V/a (b) Find the limit or show it does not exist. Justify your answer: 2 + y2 + 22. 2r sin y lim x, y) â (0,0)ã¨ã¼+1,1