Answer
$1$ unit cube
Work Step by Step
The point of intersection gives results: $\sqrt {1-x^2}=0 \implies 1-x^2=0 \\ \implies x =\pm 1$
Therefore, the volume of a solid can be computed as:
$V=\int_a^b A(x) dx=\int_{-\pi/2}^{\pi/2} (\dfrac{\cos x}{2}) \ dx \\=\dfrac{1}{2} \times 2 \int_0^{\pi/2} \cos x \ dx \\= [\sin x]_0^{\pi/2} \\=\sin \dfrac{\pi}{2}-\sin (0) \\=1 \ unit \ cube$
