1. Warm-UP!
Find the midpoint and the distance of the line between points (-4,10) and (-3,-11)

3. Algebra II – Chapter 8
8.3 Circles

4. Equation of a Circle:
A circle is the set of all points in a plane that are equidistant from a given point in the plane called the center.
The equation of a circle with center (h , k) and radius r units is:

6. How did we get that formula?
The distance from the center of the circle to the outside of the circle is the radius
So… to find the radius, we use the distance formula
But…instead of using (x,y) we use (h,k) for the center
Then…we square both sides and voila!

8. Write an Equation given a Center and a Radius:
Center (-1,-5) and radius 2 units

9. Write an Equation given a Diameter
Endpoints of the diameter are (5,4) and -2,-6)

11. Find the Center and the Radius:
The equation is:

12. Any ideas as to what we would do to find the center and radius?

13. Tonight’s Homework:
Page 429 (16-22)
Page 430 (30-35)