Question

find the area of a shaded region in each of the following figures

Answer 1

Here is ur answer. hope u understood

Answer 2

Subtracting the area of that two semi-circles from the big circle will get the area of the shaded region.

Area of shaded area =
$\pi \: {21}^{2} - \pi \: {10.5}^{2}$
Solving this will give the area of the shaded region.