BD Merit - Freelancing, BCS, Bank, Primary, Admission, NTRCA

1 . The difference between the radii of bigger circle and smaller circle is 14 cm and the difference between their areas is 1056 cm2 . Radius of the smaller circle is _

A. 7 cm
B. 5 cm
C. 9 cm
D. 3 cm

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Answer: Option B

Explanation:

Let the radius of the smaller circle be r cm
Then, radius of bigger circle = (r + 14)cm
Given, π(r + 14) 2−π(r) 2 = 1056
⇒ π(r 2 + 28r + 196)−πr 2 = 1056
⇒πr 2 + 28πr + 196π−πr 2 = 1056
⇒28 × 22/ 7 + 196x22/ 7 = 1056
= >88r + 616 = 1056
⇒r = 5 cm.

Officer (Cash) -Sonali Bank | BD Development | BD Krishi Bank - 12.10.2018

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