Question

The radius and slant height of a cone are in the ratio $4:7$. If its curved surface area is $792c{m}^2$, find its radius $(\pi =22/7)$.

Answer 1

The ratio of the radius and height of the cone is 4 : 7.

Let the radius of the cone be 4x and the height be 7x

So,

Curved surface area of the cone = πrl

792 = 22/7*4x*7x

x² = (792*7)/(22*4*7)

x² = 9

x = √9

x = 3 cm

So, the radius of the cone = 4 × 3 = 12 cm.