Question
The surface area of a sphere of radius 5 cm is five times the area of the curved surface of cone of radius 4 cm. Find the height of the cone.
Solution
Surface area of sphere of radius 4 cm = (4) cm2 when 
cm is the slant height of the cone.
According to the question,
⇒ = 5 cm ⇒
⇒ r2 + h2 = 25 ⇒ (4)2 + h2 = 25
⇒ 16 + h2 = 25 ⇒ h2 = 9
⇒ h = 3
Hence the height of the cone is 3 cm. Ans.
