Find the volume of the solid obtained by rotating the region bounded by the given curves about the specified line. Sketch the region, the solid, and a typical disk or washer.
(a) y = 2 - 1/2 x, y = 0, x = 1, x = 2; about the x-axis
(b) y = √x - 1, y = 0, x = 5; about the x-axis
(c) x = 2√y, x = 0, y = 9; about the y-axis