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The volume of a right circular cone is equal to the volume of a right circular cylinder. The height and the radius of the cylinder are 9 cm and 20 cm respectively. If the height of the cone is 108 cm, then its radius, (in cm) is
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- 12
- 14
- 20
- 10
- 12
Correct Option: D
Volume of cylinder = πr²h
= (π × 20 × 20 × 9)cu.cm.
= 3600 π cu.cm.
∴ Volume of cone = 3600π cu.cm.
| ⇒ | πR²H = 3600π | |
| 3 |
| ⇒ | × R² × 108 = 3600 | |
| 3 |
| ⇒ R² = | = 100 | |
| 108 |
→ R = √100 = 10 cm.
