The curved surface area and the height of a right circular cylinder are 660 cm2 and 10 cm respectively. Find its diameter (in cm).

Given, curved surface area of cylinder = 660 cm2

Height of cylinder = 10 cm

We know, curved surface area of cylinder = 2πrh

So, 2πrh = 660

⇒ 2 × 22/7 × r × 10 = 600

⇒ r = 21/2

So, diameter of cylinder = 2 × 21/2 = 21 cm