Let's look at the geometric characteristics of a circle. But first, please review the definition of Area Of Two-Dimensional Shapes.

- The widest length is through the center of the circle.
This length is known as the
**Diameter**of the circle; In the example, it is shown as "D" in the diameter. - If you draw a line from the exact center of the diagram
to any edge of the circle, this is called the
**Radius**; In the example, the radius is shown as "R". Also the radius is half the value of the diameter. - To compute the
**Area Of A Circle**, you will use Pi as part of the formula. - Special note, the diameter of a Circle must be greater than zero.

**Area Of A Circle Formula**

Formula = π × radius × radius =

Formula = π × r^{2}