Question

The curved surface area of a regular cylinder is given by 4πa² + 4πa - 3π Then the possible expressions for the base radius and height of the cylinder are ………. 

1) Radius = 2a – 1, height = 2a + 3 

2) Radius = 1/2 , height = 4a² + 4a - 3

3) Both options (1) and (2) 

4) Only option (2)

Answer 1

4) Only option (2) 

CSA = 2πr x h = 4πa² + 4πa - 3π

⇒ 2rh = 4a² + 4a - 3 = 4a² + 5a - 2a - 3 = 2a (2a + 3) - (2a + 3)

2rh = (2a - 1) (2a + 3)

r = 1 / 2 , h = 4a² + 4a - 3