Question

A cylinder with a radius of 1 cm and a height of 21 cm has the same volume as a cone with a height of 7 cm. What is the radius of the cone?

Answer 1

Volume of the cylinder = πr²h = π(1)² (21) = 21π cm³

Volume of the cone = 1/3 π r² h

21π = 1/3 π (r)² (7)

r³ = 21π ÷ (7/3 π) 

r² = 9

r = 3

Answer : Radius = 3