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Question
Find the area of the shaded portion in each of the following diagrams:
(i)
(ii)
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Solution
(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
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