# The volume generated by rotating the triangle with vertices at $(0,0),(3,0)$ and $(3,3)$ about $x$-axis is

$\begin{array}{1 1}(1)18\pi&(2)2\pi\\(3)36\pi&(4)9\pi\end{array}$

Required volume = Volume of the cone with base radius =3 ad height =3
$\qquad= \large\frac{1}{3}$$\pi \times 3^2 \times 3 =9 \pi$
Hence 4 is the correct answer.