Equations of a Circle

Objectives
Develop and use the equation of a circle.
Adjust the equation for a circle to move the center in a coordinate plane.
The Equation of a Circle
Given the definition of a circle: The set of all points in a plane that are equidistant from a given point called the center, we know that we are dealing with points in the coordinate plane that are a given distance, r, from a single point, the center, that we can represent with a set of coordinates that we’ll call (h, k) so that we can use them anywhere in the plane.
The Equation of a Circle, Cont.
Since we are working with Distance, the Distance Formula will be used.
The Equation of a Circle, Cont.
An equation for a circle with center at (h, k), and a radius of r units is:
Key Skills
Key Skills