$\displaystyle
A = \pi \cdot \left(\frac{x}{2\pi}\right)^2 = \frac{x^2}{4\pi}
$
Can someone tell me the steps for this? I don't get how pi(x/2pi)^2 = x^2/4pi
kmjt --
I was too tired and in too big of a hurry last night when I replied to your question. Sorry.
I should have just said to do the squaring of the terms in parenthesis, and then divide through by pi --
(x divided by 2pi) squared = x squared divided by 4pi squared. Dividing then by pi results in x squared divided by 4pi.