Tangents

1
Chapter 10

• Tangents

2
THEOREM 1
If a line is tangent to a circle, then it is
perpendicular to the radius drawn to the point of
tangency.
Example
Find the value of
3
THEOREM 2
If two segments from the same exterior point are
tangent to a circle, then they are congruent.
Example
Find the value of
If AB 1.8 cm, then AF 1.8 cm AE AF FE AE
1.8 7.0 8.8 cm If FE 7.0 cm, then DE
7.0 cm CE CD DE CE 2.4 7.0 9.4 cm
4
Example

• Is EF a tangent of circle D? Use pythag theorem!

5
Example

• You are standing at C, 8 feet away from a grain
  silo. The distance from you to a point of
  tangency is 16 feet. What is the radius of the
  silo?

• Draw it!