To find the area of a quarter circle, you simply take a quarter of a full circle. As all quarters are equal, this means that the formula would be πr24πr24. But wait, there's more. If you notice, πr24=πr22πr24=πr22. This coincides with the circle formula, just with half the radius. Notice anything? A quarter of a circle can be calculated in the same way a circle a quarter the size can. This means that a quarter circle is equal to a circle a quarter size. In this same way, a ninth of a circle is equal to a circle of one ninth the size.
