Question

In fig. 6, find the area of the shaded region, enclosed between two concentric circles of radii 7 cm and 14 cm where $\angle AOC={40}^{\circ }$. (Use $\pi =\frac{22}{7}$)

Answer 1

Given, $r=7cm$ and $R=14cm$.

Area of shaded region
= $\frac{22}{7}({14}^2-7^2)\times \frac{({360}^{\circ }-{40}^{\circ })}{{360}^{\circ }}$

= $\frac{22}{7}\times 7\times 21\times \frac{{320}^{\circ }}{{360}^{\circ }}$

= $410.67c{m}^2$