1. Tangents
Tangent - A line in the plane of a circle that intersects the circle in exactly one point.
Point of Tangency – The point of intersection between the circle and the tangent.

2. Tangents
Theorem 10.9
If a line is tangent to a circle, it is  to the radius drawn to the point of tangency.
Theorem 10.10
If a line is  to a radius of a circle at its endpoint on the circle, it is tangent to the circle.

3. Tangents
Theorem 10.11
If two segments from the same exterior point are tangent to a circle, then they are congruent.

4. is a tangent to at point D. Find a.
Answer: 15
Example 5-1c

5. a. Determine whether is tangent to
Answer: yes
Example 5-2e

6. b. Determine whether is tangent to
Answer: no
Example 5-2f

7. ALGEBRA Find a. Assume that segments that appear tangent to circles are tangent.
Answer: –6
Example 5-3d

8. Triangle NOT is circumscribed about Find the perimeter of NOT if
Answer: 172 units
Example 5-4c