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Question
The area enclosed between the concentric circles is 770cm2. If the radius of outer circle 21cm. find the radius of inner circle
Solution
Radius of outer circle = 21๐๐
Radius of inner circle = ๐ 2
Area between concentric circles = area of outer circle – area of inner circle
⇒ 770 =`22/7`(212 − R22)
⇒ 212 − ๐ 22 = 35 × 7 = 245
⇒ 441 – 245 = ๐ 22
⇒๐ 2= `sqrt(196)` = 14 ๐๐
Radius of inner circle = 14cm.
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