Let r(u, v) = (4sin(u) cos(v))i + (4sin(u) sin(v))j + (4 cos(u))k, 0

(4 sin(u) cos(L')); -k + (4 0 u 71/2, 0 L' 27K be the Let flu, v) parametrization of a surface. (a) Find the Cartesian equation for the surface. (b) Let It) = 7K/4). Calculate It) in Cartesian Coordinates and find an equation for the plane tangent to the surface, at It).