3. A point mass m is a distance d from the center of a thin spherical shell of mass M and radius R. The magnitude of the gravitational force on the point mass is given by the integral 2n 1r _ . =GM'm \"/00 (d Reos(go)) s1n(tp}' dtpd (82 + d2 2;"1'dcos(go))'V2 (a) Show that if d > R, then F(d) = 9% (b) Show that if d