area

I son't really know that yet, it might be on Kahn academy.

Why is it that when you are' finding the' area 'of a circle', you have to times the' square of the radius (r)'  by pi

When you are dealing with a circle, pi is almost always involved.   If you didn't use pi, you would be finding the area of a square with a length and width of   'r'      r x r =r^2  is the area of a SQUARE

and the equation isi'ntyour equation:

$\sqrt{2}\pi r = A \Rightarrow Area$

but the equation is really this:

$2 \pi r = A \Rightarrow Area$