A Circle

A circle, also known as a nought, is a round, two-dimensional shape. All points on the edge of the circle are at the same distance from the center.

The radius of a circle is a line from the center of the circle to a point on the side. Mathematicians use the letter \displaystyle{ r } for the length of a circle's radius. The center of a circle is the point in the very middle. It is often written as \displaystyle{ O }.