Answer
$\dfrac{\pi}{2}$
Work Step by Step
$Volume; V=2 \int_0^{\pi/2} \int_{-\cos y}^{0} \int_{0}^{-2x} \ dz \ dx \ dy$
or, $=2 \int_0^{\pi/2} \int_{-\cos y}^{0} -2x \ dx \ dy$
or, $=2 \int_0^{\pi/2} \cos^2 y \ dy$
or, $=2 [\dfrac{y}{2} +\dfrac{\sin 2y}{4}]_0^{\pi/2}$
or, $=\dfrac{\pi}{2}$
