1. How do we use circles to solve problems?

2. Parts of a Circle And Definitions
This is the exterior.
This is the interior of the circle.
A Circle is the set of all points equidistant from a given point.
That Point is called the Center.

3. A Few More Parts A Chord is a segment with endpoints on a circle.
A radius is a segment with one endpoint on the circle & one at the center.
A diameter is a chord that passes through the center.

4. Lines Involving Circles
A Secant Line touches a circle at exactly two points.
A tangent line touches a circle at exactly one point.
The Point of Tangency is that point.

5. More about Tangent Lines
A line that’s tangent to two circles is a common tangent.
This one is a common external tangent.
This one is a common internal tangent
What’s the difference?

6. Let’s Try Some B F D C E A Tangent Line Common Internal Tangent Chord
Radius
Common External Tangent
Diameter

7. Inscribed and Circumscribed
The vertices of the polygon lie on the circle.
The green circle is inscribed inside the pentagon.
The sides of the polygon
are tangent to the circle.
The green circle is circumscribed about the pentagon.

8. Now for Some Work From your books do:
p599 #s 9-10, 13-14,28, 36-37, 42-44,46, 47