Question

Find the curved surface area of a cone, if its slant height is $60$cm and the radius of its base is $21$cm.

Answer 1

We know that the curved surface area of a cone with radius $r$ and slant height $l$ is $CSA=\pi rl$.

It is given that the slant height of the cone is $l=60$ cm and the radius is $r=21$ cm, therefore,

$CSA=\pi rl=\frac{22}{7}\times 21\times 60=3960$ cm${}^2$

Hence, the curved surface area of the cone is $3960$ cm${}^2$.