Question

find the diameter of a circle whose circumference is 63.8 metre

Answer 1

Let circumference be C, diameter be d.
C=πd.
d=C/π=63.8/3.14
=31900/157~20.3m.

Answer 2

Circumference of a circle=63.8 m²

2πr=63.8

2(22/7)×r=63.8

44r/7=63.8

r=63.8×7/44

r=10.15 m

d=2r=2(10.15)

d=20.3 m

hope it helps...