Calculating the area of a circle
================================
Convert Circle -> Square. Imagine an infinite number of line
segments of length r (radius). These can easily be made into
either a circle or rectangle, depending on how you arrand them.
In a rectangle, the height of the "stacked" lines is equal to 
their length if they were arranged in a circle.
   Radius
  --------------
c |            |
i |            |
r |            |
c |            |
u |            |
m |            |
f |            |
r |            |
e |            |
n |            |
c |            |
e |------------|


However, circumfrence length is not present on center point, so:

   Radius
  --------------
c |           /
i |          /
r |         /
c |        /
u |       /
m |      /
f |     /
r |    /
e |   /
n |  /
c | /
e |/

The area of this triangle is (1/2)(Radius * Circumfrence). 
Circumfrence = 2 * pi * radius, so the area is 
(1/2)(Radius * (2 * pi * Radius))
(1/2)(2 * Radius^2 * pi)
(2/2 * Radius^2 * pi)
{pi * Radius^2}
And thus is derived the formula for the area of a circle.