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Question
Find the area of the shaded region:
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Solution
Let radius of smaller circle be r and bigger circle be R
From the figure, r = `7/2` cm and R = `7/2 + 7 = 21/2`cm
∴ Area of shaded region = Area of bigger circle – Area of smaller circle
= πR2 – πr2
= π(R2 – r2)
= `π(21/2 xx 21/2 - 7/2 xx 7/2)`
= `π(441/4 - 49/4)`
= `22/7 xx 392/4`
= 308 cm2
Hence, the area of shaded region is 308 cm2.
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