Question

The surface area of a sphere of radius 5 cm is five times the area of CSA of a cone of radius 5 cm. Then find the volume of the cone.

Answer 1

Radius of sphere = r = 5 cm 

Surface area of sphere = 4πr = 4π(5) = 100π 

Radius of cone = 5 cm 

Surface area of cone = πr(r + 1) = π5(5 + l) = 5π(5 + l) 

Surface area of sphere = 5 x 

Surface area of cone 

100π = 5 x 5π(5 + l) 

100π = 25π(5 + l)

5 + l = 100π/25π = 4

l = 4 – 5 = -1 cm 

∴ Slant height of a cone is ’-1, so problem solving is not possible.