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.
