Download Angles and Angle Bisectors

Angles and
Angle
Bisectors
Agenda
HW Check (Solving Equations Practice)
Guided Notes on Angles and Angle Bisector
CONSTRUCTION: Angle Bisector
Think. Ink. Pair. Share.
EXIT TICKET
Homework
• Page 30 #16-23, 27, 28
• Page 38, #10-12
Objectives
To identify and use the angle addition postulate.
To identify the bisector of an angle.
To use a compass and straightedge to bisect angles.
Key Questions
•What is an angle?
•How do you name an angle?
•What does it mean to be congruent?
Naming Angles
• What is an angle?
• An angle is formed by two rays with the same
endpoint. The rays are the sides of the angle. The
endpoint is the vertex of the angle.
• How do you name an angle?
1
Angle Addition Postulate
The “m”
stands for
measure of
Using the Angle Addition
Postulate
Example 1:
Using the Angle Addition
Postulate
Example 2 --This is a special example, because
the two adjacent angles together create a
straight angle.
Using the Angle Addition
Postulate
Example 3:
R
S
Given:
mRSV = x + 5
mVST = 3x - 9
V
mRST = 68
T
Find x.
Set up an equation using the Angle Addition Postulate.
Angle Bisector
• An angle bisector is a ray that divides an
angle into two congruent angles. Its
endpoint is at the angle vertex.
Angle Bisector
Example 4:
Constructing the Angle
Bisector
Congruence
What does it mean to be congruent?
If two figures have the same size and shape,
then they are congruent.
Angles with the same measure are congruent
angles.
Think.Ink.Pair.Share
• You will have 25 minutes to complete
the following practice worksheet.
Each group will be responsible for
presenting a problem to the rest of
the class.