Question

find the radius of a circle whose circumference is 57.2cm​

Answer 1

circumference of a circle= 2×pi×r

57.2cm= 2×22/7 × radius

57.2 cm ×7 = 44 × radius

400.4cm/44 = radius

radius= 9.1 cm

check:

2× pi×r

2×22/7×9.1

=57.2 cm^2

hope it helps...

Answer 2

let the radius of the circle be = R

and circumference of the circle = 2πR

So,

2πR = 57.2

2 × 22/7 × R = 57.2

R = 57.2 × 7/22 × 1/2

= 400.4/44

= 9.1 cm

so the radius of the circle is = 9.1 cm

Hope you understand the answer