Holt McDougal Geometry

12-7Circles in the Coordinate Plane9-7 Circles in the Coordinate Plane

Holt GeometryHolt McDougal Geometry

Holt McDougal Geometry

12-7Circles in the Coordinate Plane

Warm UpUse the Distance Formula to find the distance, to the nearest tenth, between each pair of points.

1.A(6, 2) and D(–3, –2)

2. C(4, 5) and D(0, 2)

Holt McDougal Geometry

12-7Circles in the Coordinate Plane

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.

Holt McDougal Geometry

12-7Circles in the Coordinate Plane

Write the equation of each circle.

J with center J (2, 2) and radius 4

Holt McDougal Geometry

12-7Circles in the Coordinate Plane

Write the equation of each circle.

K that passes through J(6, 4) and has center K(1, –8)

Holt McDougal Geometry

12-7Circles in the Coordinate Plane

Write the equation of each circle.

P with center P(0, –3) and radius 8

Holt McDougal Geometry

12-7Circles in the Coordinate Plane

Write the equation of each circle.

Q that passes through (2, 3) and has center Q(2, –1)

Holt McDougal Geometry

12-7Circles in the Coordinate Plane

Graph x2 + y2 = 16.

Graph x² + y² = 9.

Holt McDougal Geometry

12-7Circles in the Coordinate Plane

Graph (x – 3)2 + (y + 4)2 = 9.

Graph (x – 3)2 + (y + 2)2 = 4.

Holt McDougal Geometry

12-7Circles in the Coordinate Plane

Determine if the points are on, outside, or inside the circle.

ON:

Exterior:

Interior:

EX: (x-2)2 + (y-3)2 = 25.a. (2,4) b. (-3,2) c. (-5,-1) d. (0,-2)

Holt McDougal Geometry

12-7Circles in the Coordinate Plane

Lesson Quiz: Part I

Write the equation of each circle.

1. L with center L (–5, –6) and radius 9

2. D that passes through (–2, –1) and has center D(2, –4)

Holt McDougal Geometry

12-7Circles in the Coordinate Plane

Lesson Quiz: Part II

Graph each equation.

3. x2 + y2 = 4

4. (x – 2)2 + (y + 4)2 = 16