Transform the following vectors into cylindrical coordinates and then evaluate them at the indicated points: a = x(x + y) at p_1 =(1,2,3) b = x(y-x) + y(x-y) at p_2 = (1,0,2) c = xy^2/(x62 + y^2) - yx^2/(x^2 + y^2) + z4 at p_3 = (1,-1,2) d = r sin theta + theta cos theta + phi cos^2 phi at p_4 = (2, pi/2, pi/4)