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HW- Pgs. 227-228 (1-14, 23, 26)
4.1-4.3 Quiz FRIDAY 11-15-13
www.westex.org HS, Teacher Websites
11-12-13
Warm up—Geometry CPA
1. Find the measure of DBA, if mDBC = 30°,
mC= 70°, and mD = 80°.
C
B

D
A
GOAL:
I will be able to:
1. find the measures of interior and exterior angles
of triangles.
2. apply theorems about the interior and exterior
angles of triangles.
HW- Pgs. 227-228 (1-14, 23, 26)
4.1-4.3 Quiz FRIDAY 11-15-13
www.westex.org
HS, Teacher Websites
Name _________________________
Geometry CPA
4-2 Angle Relationships in Triangles
GOAL:
I will be able to:
1. find the measures of interior and exterior angles of triangles.
2. apply theorems about the interior and exterior angles of triangles.
Date ________
An ____________________ is a line that is added to a figure to aid in a proof.
Example 1: Application
Use the diagram drawn to find mXYZ.
YOU TRY:
Use the diagram to find mMJK.
A _______________ is a theorem whose proof follows directly from another theorem. Here
are two corollaries to the Triangle Sum Theorem.
Example 2: Finding Angle Measures in Right Triangles
One of the acute angles in a right triangle measures 2x°. What is the measure of the
other acute angle?
YOU TRY:
a) The measure of one of the acute angles in a right triangle is 48
measure of the other acute angle?
. What is the
The interior is the set of all points inside the figure. The exterior is the set of all points
outside the figure.
An ________________________ is formed by two sides of a triangle.
An ________________________ is formed by one side of a triangle and an extension of an
adjacent side.
4 is an exterior angle.
3 is an interior angle.
Each exterior angle has two remote interior angles. A ______________________________
is an interior angle that is not adjacent to the exterior angle.
The remote interior angles of 4 are 1 and 2.
Interior
Exterior
Example 3: Applying the Exterior Angle Theorem
Find mB.
YOU TRY:
Find mACD.
Example 4: Applying the Third Angles Theorem
Find mK and mJ.
YOU TRY:
Find mP and mT.
4-2 Practice
EXIT TICKET
Name _______________________ 11-12-13
What does the exterior angle theorem say? Give an example as part of your explanation.
EXIT TICKET
Name _______________________ 11-12-13
What does the exterior angle theorem say? Give an example as part of your explanation.
EXIT TICKET
Name _______________________ 11-12-13
What does the exterior angle theorem say? Give an example as part of your explanation.
EXIT TICKET
Name _______________________ 11-12-13
What does the exterior angle theorem say? Give an example as part of your explanation.
EXIT TICKET
Name _______________________ 11-12-13
What does the exterior angle theorem say? Give an example as part of your explanation.