Parts of a Circle
A circle is the set of all points that are a fixed distance from the center. The distance from the center to any point on the circle is the radius. For example, when a compass is used to draw a circle, the point is placed at the center, and the width of the compass opening is the radius. Because the width is always the same, as the compass is turned, the pencil draws a circle.Suppose the point represents the center of a circle. For any point in the coordinate plane, the distance from to is given by the distance formula as:
Circles in the Coordinate Plane
|Circles Centered at the Origin
Circles Centered at
By Hand: Plot the center of the circle. Use the radius to plot additional points that are 8 units up, down, left, and right from the center, and graph the circle through these points.On a Graphing Calculator: Solve for .