In a cylinder, radius is doubled and height is halved, curved surface

1.	In a cylinder, radius is doubled and height is halved, curved surface area will be(A) halved (B) doubled (C) same (D) four times
Answer» (C) same Explanation: Let the radius of a cylinder = r unit Let the height of a cylinder = h unit. According to question, Radius is doubled = 2r Height is halved = h/2 Then, Curved surface area of a cylinder = 2 × π × r × h And according to the above condition, Curved surface area = 2 × π × 2 × r × h/2 = 2 × π × r × h This is same as the curved surface area of the cylinder with radius r and height h. Hence, option C is the correct answer.

In a cylinder, radius is doubled and height is halved, curved surface area will be(A) halved (B) doubled (C) same (D) four times

Answer»

(C) same

Explanation:

Let the radius of a cylinder = r unit

Let the height of a cylinder = h unit.

According to question,

Radius is doubled = 2r

Height is halved = h/2

Then,

Curved surface area of a cylinder = 2 × π × r × h

And according to the above condition,

Curved surface area = 2 × π × 2 × r × h/2

= 2 × π × r × h

This is same as the curved surface area of the cylinder with radius r and height h.

Hence, option C is the correct answer.