Question

Are of 2 circles are in the ratio 25:36.Find the ratio of their circumference.

Answer 1

they will be in the ratio 5:6

formula from 2d to 1d just root the ratio
from 1d to 2d just square the ratio

Answer 2

by given,
$\pi\ \: \: {r}^{2} \div\pi\ \: {r}^{2} = 25 \div 36$
r^2 /r^2 =25/36
r/r=5/6
$2\pi \: r \div 2\pi \: r = 5 \div 6$

the ratio of their circumference is 5:6