10 6 Circles in Coordinate Geometry Obj Copyright

10. 6: Circles in Coordinate Geometry Obj: _____________________________ Copyright © by Holt, Rinehart and Winston. All Rights Reserved.

Standard form for a circle • (x – h)2 + (y – k)2 = r 2 – (h, k) is the Center of the circle – r is the Radius Copyright © by Holt, Rinehart and Winston. All Rights Reserved.

Examples • 1) Given: (x – 7)2 + (y +3)2 = 36, find the center and the radius. Copyright © by Holt, Rinehart and Winston. All Rights Reserved.

9. 6 Circles in the Coordinate Plane Examples: 2) Sketch a circle from its equation. Sketch the circle (x – 2)² + (y + 1)² = 9. The circle has center at (2, – 1) and radius 3. Copyright © by Holt, Rinehart and Winston. All Rights Reserved.

9. 6 Circles in the Coordinate Plane Key Skills Write the equation of a given circle. Write an equation of a circle with center (– 4, 6) and radius 9. TOC Copyright © by Holt, Rinehart and Winston. All Rights Reserved.

Practice Copyright © by Holt, Rinehart and Winston. All Rights Reserved.

Find the x- and y-intercepts for the graph of each circle 2) x 2 + y 2 = 49 3) x 2 + (y+22) = 36 Copyright © by Holt, Rinehart and Winston. All Rights Reserved.

Find the center and radius of each circle 5) (x+1)2 + y 2=14 6) (x+3)2 + (y-5)2 = 31 Copyright © by Holt, Rinehart and Winston. All Rights Reserved.

Write an equation for the circle with the given center and radius 7) Center (4, 3), r = 5 8) Center (-1, 5) r = 3 Copyright © by Holt, Rinehart and Winston. All Rights Reserved.

Graph the circle on a graphing calculator and show Ms. Thelen 9) (x+3)2 + y 2 = 36 Copyright © by Holt, Rinehart and Winston. All Rights Reserved.