2'. (a) (10 points) Find Btu/62L when u = 7r, 1; = if if m = my + 111(2), 53 = 32/15, y=u+v, z=cosu. (b) (10 points) Find the directional derivative of f(:r:,y,z) = efE sin(4y + 32) at PO(D,0,U) in the direction of v = i + 2j 2k. Find a unit vector in the di- rection Where the function increases most rapidly at P0