Question

it is a very easy question plz try to help. u just have to solve it

(απ$R^{2}$)x 0 +[απ$[ \frac{R}{2}]^{2}$] $\frac{R}{2}$
whole divided by
απ$R^{2}$ + απ$[\frac{R}{2}]^{2}$

Answer 1

$\frac{( \alpha \pi R^2)*0+[ \alpha \pi (\frac{R}{2})^2]*\frac{R}{2} } { \alpha \pi R^2+ \alpha \pi [\frac{R}{2}]^2}\\\\=\frac{\frac{R}{4}}{1+\frac{1}{4}}\\\\=\frac{R}{5}$