1. Section 1.5: Circles
Definition circle: Set of points a fixed distance from a center point.
Definition radius: Distance from center to any point on the circle.

2. Section 1.5: Circles
Sketch the graph of a circle with center (1,2) and radius = 4 . .
2. Identify the center and radius

3. 1. Standard Form of the Equation of a Circle
Let be
a point on the circle.
Standard Form:
are the coordinates of the circle center.
is the radius of the circle.

4. 2. Write the equation of the circle if you are given the radius and center
3) Write the standard form of the equation of a circle with center at (4, -3) and radius r = 4
4) Determine the x and y intercepts

5. Find the center and radius from the equation written in standard form
Identify the center and radius for the following equations of circles. Determine the x and y intercepts 5. 6. 7.
Prove (algebraically) that the circle in #6 crosses into the 4th quadrant.

6. 3. Determine the equation of the circle when given 2 points on the circle
8) Determine the equation in standard form for the circle with endpoints of diameter at (4,3) and (0,1).