4. Evaluate the following integrals by converting to polar coordinates. (a) / sin (Vaz + y') dA, where R = ((2,4) | 72 6 27 + 1' 6 47'). (b) (2y - z) dA, where R is the region in the first quadrant enclosed by the circle x2 + y? = 9 and the coordinate axes. 5. Evaluate the following integrals by applying the given change of variables. (2) 31 -V * - 24 dA, where R is the region bounded by x - 2y = 0, x - 2y = 4, 3x - y = 1, 3x - y = 8, using -u+ 2v -3u + v 1 = 5 , 1/= 5 (b) / zy' dA, where R is the region in the first quadrant bounded by y = x, y = 4x, xy = 1, xy = 4, using * = =, y=v