Question

Find the area of the shaded portion in each of the following diagrams :

Answer 1

Radius of circle, r =7 cm

$\therefore$ Side of Square =7 +7 =14 cm

Area of circle $=\pi r^2$

$=\frac{22}{7}\times 7\times 7$

$=154c{m}^2$

Area of Square $=14\times 14$

$=196c{m}^2$

$\therefore$ Area of Shaded portion =196-157

$=42c{m}^2$

(ii)Radii of concentric circle are

$r_1=4.5m$

$r_2=2.5m$

$\therefore$ Area of shaded protion $=\pi r_1^2-\pi r_2^2$

$=\pi [r_1^2-r_2^2]=\frac{22}{7}\left[\right(4.5{)}^2-\left(2.5{)}^2\right]$

$=\frac{22}{7}\times (4.5+2.5)(4.5-2.5)$

$=\frac{22}{7}\times 14=44c{m}^2$