Question

Find the circumference of circle having following radius (π = 22/7)

(i) 21 cm

(ii) 28 cm

(iii) 10.5 cm

Answer 1

(i) Radius of circle = 21 cm

Circumference of Circle = 2πr

= 2 x 22/7 x 21 = 2 x 22 x 3 = 44 x 3

= 132 cm

(ii) Radius of circle = 28 mm

circumference = 2πr

= 2 x 22/7 x 28 = 2 x 22 x 4 = 2 x 88

= 176 cm

(iii) Radius of circle = 10.5 cm

Circumference of circle = 2πr

= 2 x 22/7 x 10.5

= 2 x 22 x 1.5

= 44 x 1.5 = 66 cm.