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If S denotes the area of the curved surface of a right circular cone of height h and semivertical angle a then S equals
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- πh² tan²α
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1 πh² tanα 3
- πh² secα tanα
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1 πh² secα tanα 3
- πh² tan²α
Correct Option: C
AD = h
| tan α = | |
| AD |
⇒ BD = h tanα
∴ Radius (r) = h tanα
∴ l = √h² + r²
= √h² + h² tan²α
= √h² (1 + tan²α)
= √h² sec²α = h secα
∴ Curved Surface area of the circular cone = πrl
= π × h tanα . h secα
= πh² secα. tanα
