The area of a circle follows the formula of 3.14 times radius². For an example, let's use the Louisiana Superdome.
Louisiana_Superdome.jpg
The diameter of the Superdome is 250.32 yards to find the radius we half that, so the radius is 125.16. when we square that we get 15,665.03 yards. When we times it by 3.14 we get 49,188.19 yards².