Question

In the figure alongside, crescent is formed by two circles which touch at the point $A$. $O$ is the centre of the bigger circle. If radius of smaller circle is $=5cm$ and radius of larger circle is $9cm,$ find the area of the shaded region. (Take $\pi =3.14$ )

Answer 1

The area of shaded region is given by area of bigger circle - area of smaller circle

Area of larger circle $\pi r^2=\pi 9^2=81\pi$

Area of smaller circle $\pi r^2=\pi 5^2=25\pi$

Area f shaded region is $81\pi -25\pi =56\pi =56\left(3.14\right)=175.84{\text{cm}}^2$