Question

The radius of a cone is $3cm$ and vertical height is $4cm$. Find the area of the curved surface.

• A. $62.85{cm}^2$
• B. $66.05{cm}^2$
• C. $52.25{cm}^2$
• D. $47.14{cm}^2$

Answer 1

The correct option is D $47.14{cm}^2$

Curved surface area of a cone $=\pi rl$

For a cone, $l=\sqrt{h^2+r^2}$

Hence, $l=\sqrt{3^2+4^2}$

$l=5cm$
So, CSA of this cone, $=\frac{22}{7}\times 3\times 5=47.14{cm}^2$