Download 4-2 Angles of Triangles

Geometry

Monday
12/8/14
Warm-ups
◦ Work with a partner to complete pg. 184



Check in/Discuss 4.1 Practice WS
Today, you will be able to:
Discussion/Notes/Guided Practice
◦ Section 4.2 Angles of Triangles

Apply the Angle Sum Theorem
Assignment:

Apply the Exterior Angle
Theorem
◦ A#4.2 page 188 # 1, 2, 10-27 all
◦ Begin studying for Quiz – Sections 4.1,
4.2, 4.6
Success Criteria:

Quiz
Sections 4.1, 4.2, 4.6
Thurs 12/9
Q&A
 Guided Practice
 Homework
Spirit Week Tues:
Favorite Character Day
Angle Sum Theorem
The sum of the measures of the angles of a triangle is ______.
Given:  ABC
Prove: m4  m5  m2  180
Example 1

Find the missing angle measures.
Guided Practice
Self-Evaluation - Rate each learning target:
Apply the Angle Sum Theorem
4
3
2
1
0
Example & Guided Practice
Exterior Angle Theorem

Find the missing angle lengths in the
following triangles:
1.
2.
105
138
58
112
Self-Evaluation - Rate each learning target:
Apply the Exterior Angle Theorem
4
3
2
1
0
Proving Exterior Angles
Theorem by Induction
Based on the previous examples we can
make the conjecture that…
Proving the Exterior Angles
Theorem Deductively
2
1
3
4
Example 2

Find the measure of each numbered
angle in the figure
Guided Practice for Example 2
Self-Evaluation - Rate each learning target:
Apply the Angle Sum and Exterior Angle Theorems
4
3
2
1
0