1. 15.3 Tangents and Circumscribed Angles
What are the key theorems about tangents to a circle?

2. Tangent- a line in the same plane as a circle that intersects the circle in exactly one point
Point of tangency- the point where a tangent and a circle intersect
The line is tangent to circle
C and point P is the
point of tangency.

3. Tangent-Radius Theorem:
If a line is tangent to a circle, then it is perpendicular to a radius drawn to the point of tangency

4. Example: Is EF tangent to Circle D?61 11 F E 60

5. Circumscribed Angle- an angle formed by 2 rays from a common endpoint that are tangent to a circle

6. A B D C
m<ABC + m<ADC = 180°

7. XA and XB are tangent lines to Circle C. Find m<X.
(2y)°
(4y)°

8. Tear out Pages 800-803 and circle
the following problems:
5, 6, 10, 11, 13, 19
Tear out Page and circle
8, 9, 12, 13, 14

9. p ° °
<P= 90, <Q=140
<R=90, <S=40
<D=65, <A=70
<B= 115, <C=110
<W=94, <V= 101
<T=79, <U=86
<J= 108°
<K= 81°
<L= 72°
<M= 99°
p (set sides equal to each other and you will need to use the quadratic formula) ° ° °