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The area enclosed between the concentric circles is 770cm2. If the radius of outer circle 21cm. find the radius of inner circle
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Radius of outer circle = 21ЁЭСРЁЭСЪ
Radius of inner circle = ЁЭСЕ2
Area between concentric circles = area of outer circle – area of inner circle
⇒ 770 =`22/7`(212 − R22)
⇒ 212 − ЁЭСЕ22 = 35 × 7 = 245
⇒ 441 – 245 = ЁЭСЕ22
⇒ЁЭСЕ2= `sqrt(196)` = 14 ЁЭСРЁЭСЪ
Radius of inner circle = 14cm.
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