Question

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

(i)

(ii)

Answer 1

(i)

Radius of circle, r = 7 cm

∴ Side of square = 7 + 7 = 14 cm

Area of circle = `pir^2`

= `22/7 xx 7xx 7`

= 154 cm²

Area of square = `14 xx 14`

= 196 cm²

∴ Area of shaded portion = 196 - 154

= 42 cm²

(ii)

Radii of concentric circles are

`r_1 = 4.5`m

`r_2 = 2.5`m

∴ Area of shaded portion = `pir_1^2 - pir_2^2`

= `pi[r_1^2 - r_2^2] = 22/7[(4.5)^2 - (2.5)^2]`

= `22/7 xx (4.5 + 2.5) (4.5 - 2.5)`

= `22/7 xx 14 = 44` cm²