Show that the surface area of the solid region bounded by the three cylinders x2 + y2 = 1, y2 + z2 = 1 and x2 + z2 = 1 is 48 - 24V2. Hint: Evaluate the surface area of the graph of f (x, y) = V1 - x2 over the region R = {(r, 0) E 12 | 0