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Question
The diameter of a circle is 42 cm, find its perimeter. If the perimeter of the circle is doubled, what will be the radius of the new circle? (Take π = `22/7`)
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Solution
Given, the Diameter of a circle = 42 cm
∴ Radius of circle = `42/2` = 21 cm
The perimeter of the circle = 2πr
=`2xx22/7xx21`
= 132 cm
If the perimeter of the circle doubled
= 2 × 132 =264 cm
Radius = `"C"/(2π)=264/(2xx22/7)`
= `(264xx7)/(2xx22)`
= 42 cm
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