2. Let u(x, y) = e* cos(y) for any (x,y) = R. Define B, ((0,)) to be the ball whose center is (0, 3) and whose radius is some positive number r. Denote aB, ((0,3)) to be the boundary of the ball Br((0,)). (a) Show that u is a harmonic function. (b) Compute [u(x,y) ds. a,((0,4))