Processing math: 45%
Home / Aptitude Tests / Mathematics / The height of a righ...
The height of a right circular cone is 4cm. The radius of it...

The height of a right circular cone is 4cm. The radius of its base is 3cm. Find the curved surface area

A.

9πcm2

B.

15πcm2

C.

16πcm2

D.

20πcm2

Correct answer is B

Curved surface area or a cone =πrl
from the information l^2 = 4^2 + 3^2 = 16+9\\ l = \sqrt{25} = 5; ∴ C.S.A\hspace{1mm} = \frac{22}{7}\times 3 \times 5\\ Since \frac{22}{7}=\pi ∴ C.S.A\hspace{1mm} =\hspace{1mm}15\pi