Find the area of base and radius of a cylinder if its curved surface a

1.	Find the area of base and radius of a cylinder if its curved surface area is 660 sq.cm and height is 21 cm.
Answer» Given: Curved surface area = 660 sq.cm, and height = 21 cm To find: area of base and radius of a cylinder i. Curved surface area of cylinder = 2πrh ∴ 660 = 2 x (22/7) x r x 21 ∴ 660 = 2 x 22 x r x 3 ∴ 660/2 x 22 x 3 = r 660/2 x 66 = r ∴ 5 = r i.e., r = 5 cm ii. Area of a base of the cylinder = πr² = (22/7) x 5 x 5 = 550/7 = 78.57 sq.cm ∴The radius of the cylinder is 5 cm and the area of its base is 78.57 sq.cm.

Find the area of base and radius of a cylinder if its curved surface area is 660 sq.cm and height is 21 cm.

Answer»

Given: Curved surface area = 660 sq.cm, and height = 21 cm

To find: area of base and radius of a cylinder

i. Curved surface area of cylinder = 2πrh

∴ 660 = 2 x (22/7) x r x 21

∴ 660 = 2 x 22 x r x 3

∴ 660/2 x 22 x 3 = r

660/2 x 66 = r

∴ 5 = r

i.e., r = 5 cm

ii. Area of a base of the cylinder = πr²

= (22/7) x 5 x 5

= 550/7

= 78.57 sq.cm

∴The radius of the cylinder is 5 cm and the area of its base is 78.57 sq.cm.