Find the area of a sector of a circle with radius 7 cm if the angle of the sector is 60°.               [Page No. 148]

$$\begin{aligned} \text{Area} &= \pi r^2 \times \frac{\theta}{360^\circ} \\ &= \frac{22}{7} \times 7^2 \times \frac{60}{360} \\ &= \frac{22}{7} \times 49 \times \frac{1}{6} \\ &= 22 \times \frac{7}{6} \\ &= \frac{77}{3} \approx 25.67 \text{ cm}^2 \end{aligned}$$

Concept Applied
The length of an arc subtending angle at the centre is $\frac{\theta}{360^{\circ}}\times 2\pi r^{2}$,
and the area of the corresponding sector is $\frac{\theta}{360^{\circ}}\times \pi r^{2}$.