Multiple choice

The diameter of the base of a right circular cylinder is $21\mathrm { cm }$ and its height is $10\ \mathrm { cm }$ . What is the area of the curved surface?

  1. $660\mathrm { cm } ^ { 2 }$
  2. $930\mathrm { cm } ^ { 2 }$
  3. $1320\mathrm { cm } ^ { 2 }$
  4. $640\mathrm { cm } ^ { 2 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Curved surface area of a cylinder = 2 * pi * r * h. Diameter = 21, so radius r = 10.5. Area = 2 * (22/7) * 10.5 * 10 = 2 * 22 * 1.5 * 10 = 660.

AI explanation

The curved surface area of a cylinder is found by the formula 2 pi r h. With a diameter of 21 cm, the radius r is 10.5 cm, and the height h is 10 cm. Calculating 2 times 22/7 times 10.5 times 10 gives 660 square cm.

Keep practicing — related questions