Answer
$18\pi$
Work Step by Step
Setup the integration using disk method about the x-axis
$\pi \int_0^3 (\sqrt {9-x^2)}dx$
$\pi \int _0^3 (9-x^2)dx$, Integrate
$\pi [9x-\frac{1}{3}x^3]_0^3$, Evaluate the definite integral
$\pi(27-9)$, Simplify
$18\pi$
