Question

Someone help me I don’t understand the circumference C=2TTr

Answer 1

You are being asked to make π the subject in

$C=2πr \:$

So divide both sides of the equation by
$2r$

That is

$\frac{ C}{2r} = \frac{2πr}{2r}$
The you have
$\frac{ C}{2r} = \pi$

or

$\pi = \frac{ C}{2r}$

I hope this is helpful?