Question

Two circles have areas of 16(pi) and 25(pi). Find the ratio of their circumferences.

Answer 1

First off you should memorize and know this:
\[\pi = {c \over d}\]

Answer 2

c is circumference
d is diameter

Answer 3

Also memorize and know:
\[Area \space of \space a \space circle = \pi r^2\]

Answer 4

r is the radius

Answer 5

Sorry There was mistake in the last step..

Answer 6

So we know the areas... with that information we can find the radius of both circles using the formula I posted

Answer 7

Lets plug the first one in

Answer 8

4/5
as ratio of there ara is 16/25=R^2/R^2
thus ratios of perimeter would be r/R then taking aquare root we have r/R=4/5

Answer 9

okay sweet the pi's cancel