Equation of a Circle (Jump to: Lecture | Video )

A circle is a set of all points on a plane that are the same distance from a center point.

Figure 1.

Above we have a circle with a center at (2, 0) and a radius of 4.

Equation of a Circle
The standard equation of a circle is written in the form:

The equation of our circle above would therefore be:

Figure 2.