• # question_answer 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 $\pi =\frac{22}{7}$)

 Given, $r=7\text{ }cm$ and $R=14\text{ }cm$ . Area of shaded region $=\pi ({{R}^{2}}-{{r}^{2}})\frac{\theta }{360{}^\circ }$ $=\frac{22}{7}({{14}^{2}}-{{7}^{2}})\times \frac{(360{}^\circ -40{}^\circ )}{360{}^\circ }$ $=\frac{22}{7}\times 7\times 21\times \frac{320{}^\circ }{360{}^\circ }$ $=410.67\,\,c{{m}^{2}}$