The surface area of a sphere of radius 5 cm is five times the area of

1.	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» 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.

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»

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.