## Elementary Geometry for College Students (5th Edition)

a) $90\pi$ b) $90\pi$
a) The radius is 5, and the height is 9, so we obtain: $A = 2\pi rh = 2\pi (5)(9) = 90\pi$ b) The radius is 9, and the height is 5, so we obtain: $A = 2\pi rh = 2\pi (9)(5) = 90\pi$