Wed 4/13 Lesson 10 – 3 Learning Objective: To graph circles Hw: Pg. 634 #5 – 61 eoo, skip 13, 47

Algebra II

 To graph circles

Circle – Set of all points in a plane that are a distance r (radius) from a given point (center of the circle).

 Determine where the center (h, k) is  Determine what the radius r is  If given center, and a point on the circle, find the distance between the center and the point  If given the endpoints of the diameter, find the distance of the diameter then divide by 2  Plug into the standard form of an equation of a circle

1. Center (-4, 3), radius 4 2. Center (5,-2), radius 8

3. Center (-8, -3), point on the circle (-8, 8)

4. Endpoints of a diameter (5, 0) & (-5, 0)

 Get into standard form by completing the square  Determine where the center (h, k) is  Determine what the radius r is  Plot a point on the center  Count the radius r up, down, left, right from the center  Graph a circle using those four points  OR graph by translation of parent graph

Radius: 4 Center: (0, 0)

Radius: 2 Center: (-3, 2)

#3 should have “3 units down and 5 units right” #4 CROSS OFF “3 units down and 5 units right”

Radius: 2 Center: (5, -3)

Radius: 4 Center: (0, -3)

Center: (3, -2)

Center: (-1, -3) 9