The formula for the area of a circle is given as [tex]A= \pi r^2[/tex], where r is the radius of the circle. Using r for 13, and a truncated value of 3.14 for pi, we write [tex]A=3.14(13)^2=3.14(169)=530.66 \ ft^2[/tex]. The actual proof for this formula involves a bit calculus, so for now, it's probably best to just memorize he formula.
