Equations of Circles Notes
Equations of Circles
Equations of Circles
Definitions
• A circle is the set of all points in a plane that are equidistant from a given point called the center of the circle. A circle with center P is called “circle P” or Standard Form for an equation of a Circle:
• The distance across the circle, through its center, is the diameter of the circle. • The distance from the center to a point on the circle is the radius of the circle. • Two circles are congruent if they have the same radius. 1. Write the equation of a circle with center (­4,3) and radius 4
Find the center and radius for the following:
3.
2.
Equations of Circles
4. Translate x2+y2=9 two units up and left 5 units
Graph:
5.
6.
Equations of Circles
Write the equation of the circle in standard form.
Equations of Circles
The endpoints of a diameter of a circle are (­4, 7) and (2, ­1). What is the equation of the circle in standard form?