Question

The curved surface area of a right circular cone of height $15$ cm and base diameter $16$ cm is __________.

• A. $60\pi {\text{cm}}^2$
• B. $68\pi {\text{cm}}^2$
• C. $120\pi {\text{cm}}^2$
• D. $136\pi {\text{cm}}^2$

Answer 1

The correct option is D $136\pi {\text{cm}}^2$

We know, the curved surface area of a right circular cone $=\pi rl$.

Slant height $l=\sqrt{h^2+r^2}$

$\Rightarrow l=(\sqrt{8^2}+{15}^2)$

$\Rightarrow l=17$ cm.

Now substitute the value in above equation, we have,

the curved surface area $=\pi \times 8\times 17$

$=136\pi {\text{cm}}^2$.

Therefore, option $D$ is the correct.