Question

The height of a right circular cylinder is 6 m. If three times the sum of the areas of its two circular faces is twice the area of the curved surface, then the radius of the base is 

(a) 4 m 

(b) 3 m 

(c) 2 m 

(d) 1 m

Answer 1

(a) 4 m

Let the radius and height of the cylinder be r m and h m respectively. Then,

3(πr² + πr²) = 2 x 2πr x 6

⇒ 6πr² = 24πr ⇒ r = 4 m.