Question

How to do ?????????????

Answer 1

Here is your answer in attachment

hope it help you

Answer 2

in the above diagram
the shaded part is half the circle
area of shaded region is half the area of circle
$area \: of \: circle \: = \pi {r}^{2} \\ area \: of \: shaded \: region \: = \frac{\pi {r}^{2} }{2} \\ = \frac{\pi( {4}^{2}) }{2} \\ = 8\pi \: {cm}^{2}$
hope it helps