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From a solid right circular cylinder of length 4 cm and diameter 6 cm, a conical cavity of the same height and base is hollowed out. The whole surface of the remaining solid (in square cm.) is
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- 48π
- 15π
- 63π
- 24π
- 48π
Correct Option: A
Whole surface of the remaining solid = 2πrh + πr² + πrl
where l = slant height of cone. l = √r² + h² = √3² + 4²
= √9 + 16 = √25 = 5 cm
∴ Required area = (2 × π × 4 × 3 + π × 3 × 3 + π × 3 × 5) square cm.
= (24π + 9π + 15π) square cm. = 48π square cm.
