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Question
Find the radius and area of a circle, whose circumference is :
(i) 132 cm
(ii) 22 m
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Solution
(i)
Circumference of circle = 132 cm
2πr = 132
`2 xx 22/7 xx r = 132`
`r = (132 xx 7)/(2 xx 22)`
`r = 21`cm
∴ Area of circle = `pir^2`
= `22/7 xx 21 xx 21`
= 1386 cm2
(ii)
circumference of circle = 22 m
∴ `2pir = 22`
`2 xx 22/7 xx r = 22`
`r = (22 xx 7)/(2 xx 22)`
r = `7/2`
r = 3.5 m
Area of circle = `pir^2`
= `22/7 xx 3.5 xx 3.5`
= 38.5 m2
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