Question

Pair of concentric circle are given, find the area of shaded region if radius of smaller and bigger circle are 7 cm and 14 cm respectively.

• A. 154 $c{m}^2$
• B. 308 $c{m}^2$
• C. 462 $c{m}^2$
• D. 616 $c{m}^2$

Answer 1

The correct option is C 462 $c{m}^2$

Area of shaded region
= Area of bigger circle - Area of smaller circle
= Area of ring = $\pi$$(R^2$- $r^2)$
....where R and r are radii of bigger and smaller circles respectively.

Given: R = 14 cm, r = 7 cm
We know,
Area of shaded region = $\pi$$(R^2$- $r^2)$
= $\frac{22}{7}$$\times$$({14}^2$- $7^2)$
= $\frac{22}{7}$$\times$147
= 22$\times$21 = 462 $c{m}^2$
Area of shaded region is 462 $c{m}^2$.