1. 10-5: Tangents

2. Definitions
tangent – a line that intersects the circle at just one point.
point of tangency – the intersection point.
If a radius and a tangent intersect, they are perpendicular.

3. EX: Segment BC is tangent to circle A at point B. Find AC.

4. Theorem:
If a line is perpendicular to a radius of a circle at its endpoint on the circle, then the line is tangent to the circle.

5. EX: Is BC tangent to circle A?

6. Theorem:
If two segments from the same exterior point are tangent to a circle, then they are congruent.

7. EX: Find x.

8. EX: If EC=3DF, find the perimeter of triangle ADC

9. Assignment:
p. 556; 8-20, 23-26, 37-40