Angles Formed by Secants and Tangents
Section 9.4
Pg. 588
Mrs. Riggle
Lesson Objectives
Today we will learn how to:
• Define angles formed by secants and
tangents of circles.
• Use theorems about measures of arcs
intercepted by these angles.
Classifications of Angles with Circles
Case 1: Vertex On Circle
Find each measure:
m<BCD
mABC
Case 2: Vertex Inside Circle
Find the angle measure:
m<SQR
Case 3: Vertex Outside Circle
Find the value of x:
Summary
You try!
Remember
-Vertex On Circle = ½ measure of the arc.
-Vertex Inside Circle = ½ sum of the intercepted arcs.
-Vertex Outside Circle = ½ difference of the intercepted arcs.
Assignment
Independent Work
Work to be Submitted
Pgs. 593–594, #11–25, odds.
Check your answers in the
back of the textbook when
you are finished.
9.4 EdMastery Assignment
Due 4p.m. Friday, April 15,
2011.
Have a nice weekend!