Question

A cylinder has a surface area of 339cm. The radius is two times greater than the height. what is the radius of the cylinder.

Answer 1

The answer is 6 cm.

The surface area of the cylinder is:
SA = 2πr² + 2πrh

SA = 339
r = 2h
⇒ h = r/2
r = ?
π = 3.14

339 = 2πr² + 2πr*r/2
339 = 2πr² + πr*r
339 = 3πr²
πr² = 339/3
πr² = 113
r² = 113/π
r² = 113/3.14
r² ≈ 36
r = √36
r = 6