5. (12 points) (Textbook 5.105) A modem transmits a two-dimensional signal (X, Y) given by: X = rcos(270/4) and Y = rsin(270/4) where O is a discrete uniform random variable in the set {0, 1, 2, 3} The joint pmf of X and Y are shown in the table below: X -r 0 Y -r 0 0.25 0 0 0.25 0 0.25 0 0.25 0 (a) Find Pyly|X = r] and Px [x|Y = 0]. (b) Find E[Y X = 0]. (c) Find E[XY[X = r] and E[XY]