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The difference between the radii of the bigger circle and smaller circle is 14 cm and the difference between their areas is 1056 cm². Radius of the smaller circle is
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- 7 cm
- 5 cm
- 9 cm
- 3 cm
- 7 cm
Correct Option: B
Using Rule 14,
Radius of the larger circle = R cm
Radius of the smaller circle = r cm
∴ R – r = 14 cm
and π (R²– r²) = 1056
| ⇒ R²– r² = | = | ||
| π | 22 |
π R²– r² = 336
π (R + r) (R – r) = 336
| ⇒ R + r = | = 24 cm. | |
| 14 |
∴ (R + r) – (R – r) = 24 – 14
⇒ 2r = 10 ⇒ r = 5 cm
