Question

The radius and slant height of a cone are in the ratio 21 : 24. If the curved surface area of the cone is 1188 cm2 , then its radius is ____

. A. 38.14 cm B. 21 cm C. 18.18 cm D. 10.5 cm

Answer 1

The radius and slant height of a cone are in the ratio 21 : 24.

Let radius of the cone = 21x

And slant height of the cone = 24x

 curved surface area of the cone = πrl = 1188 cm2

⇒  22/ 7 ×21x ×24x = 1188

x2 = 1188 / (66 × 24) = 0.75 cm = 3 / 4 cm

x = √3 / 2.

∴ radius of the cone = 21x = 21 × √3 / 2 = 18. 186 cm