The area of the base of a right circular cone is 81π cm2 its height is 12 cm. What is curved surface area (in cm2) of the cone?
A. 126π
B. 135π
C. 108π
D. 144π
Answer: Option B
Solution (By Examveda Team)
πr2 = 81πr = 9
Curved surface area of cone = πr$$l$$
$$l$$ = $$\sqrt {{{12}^2} + {9^2}} $$
$$l$$ = 15
Curved surface area = π × 9 × 15 = 135π
This Question Belongs to Arithmetic Ability >> Mensuration 3D
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