S.178 T.466

a) $V=\frac{\frac{4}{3}\pi\cdot\left(\frac{20}{2}\right)^3}{2}=2094{,}395...\approx2100\left(cm^3\right)$
b)
$A=\frac{4\pi\cdot\left(\frac{20}{2}\right)^2}{2}=200\pi=628{,}318...\approx628\left(cm^2\right)$
c)
$2100\cdot\frac{45}{360}=262{,}5\approx260\left(cm^3\right)$