1. Circles in the Coordinate Plane
Geometry 11-5

2. Get your supplies
Graph Paper
Compass?
Equation Exploration

3. Make a table of values to graph the equation x2+y2=4
Complete enough of your table of values to complete the graph
Equation Exploration

4. Equation Exploration You should have graphed a complete circle.
What is the radius of the circle?
Re-write the equation of the circle using the radius instead of a number.
Equation Exploration

5. (x-3)2+(y-3)2=9 Equation Exploration
Make another table of values to graph the equation
(x-3)2+(y-3)2=9
Complete enough of your table of values to complete the graph
Equation Exploration

6. Equation Exploration (x-3)2+(y-3)2=9
What are the coordinates of the center of the circle?
(3,3)
Equation Exploration

7. Equation Exploration (x-3)2+(y-3)2=9 What is the radius of the circle?

8. Equation Exploration (x+2)2+(y-4)2=16
What are the coordinates of the center of the above circle equation?
(-2,4)
Equation Exploration

9. What is the radius of a circle defined by the following equation?
x2+y2=49
The radius is 7
Equation Exploration

10. Standard Equation of a Circle
The standard equation for a circle is written in the following form
(x-h)2 + (y-k)2 = r2
The radius of the circle is r
The center of the circle is (h,k)
Standard Equation of a Circle

11. Example

12. Example

13. Example

14. Example

15. Example

16. Circles in the Coordinate Plane
Sample Problems

17. Center = (0,4)
Radius = 3

18. Center = (5,0)
Radius = 4

19. Center = (-1,1)
Radius = 2

20. Center = (-4,2)
Radius = 5

21. (x)2+(y)2=9

22. (x)2+(y-2)2=4

23. (x-1)2+(y-1)2=1

24. (x)2+(y-1)2=4

25. (x-3)2+(y-3)2=16

26. Practice

27. Practice

28. Practice

29. Practice

30. Practice

31. Practice

32. Practice

33. Practice

34. Interior On
Exterior
Exterior On
Interior

35. Pages 617 – 619
2, 6, 8, 10, 12, 16, 18, 28, 30, 32, 34, 36
Homework

36. Honors Homework Pages 617 – 619
2, 6, 8, 10, 12, 16, 18, 28, 30, 32, 34, 36, 64
Honors Homework