1. Graphing Circles and Writing Equations of Circles

2. Here is the “Circle Song” R squared equals X minus H squared Plus Y minus K squared You can now graph a circle To the tune of Happy Birthday to You

3. Graphing Circles The equation of a circle is based on the Distance Formula and the fact that all points on a circle are equidistant from the center.

4. The Equation of a Circle r = radius (take the square root of r 2 ) the center point = (h,k) (change the signs from the equation)

5. Example 1 Write the equation of a circle with a center at ( -3, 4) and a radius of 2

6. Example 2 Write the equation of a circle with a center at ( 0, 7) and a radius of 1.5

7. Graphing a circle Graph the equation C = (2,4)r = 4

8. Graphing a circle Graph the equation C = (-4,3)r = 5

9. Graphing a circle Graph the equation C = (-5,-1)r =√55 = 7.4

10. Graphing a circle Graph the equation C = (0, 3)r =√40 = 6.3

11. Graphing a circle Write the equation C = (2,4)r = 4

12. Graphing a circle Write the Equation C = (4,0)r = 5