Download Framework for Learning: Angles in Triangles – Exterior Angles

Angles in Triangles –
Exterior Angles
Framework for Learning:
Leader’s Name: ………………………………….
Co-Leader’s Name: ……………………………..
Instructor’s Initials: ………
___________________________________________________________________________________
Getting Started:
Log into UMATH X
From the menu on the left:
Hover over the Strand: Measurement & Geometry
Hover over Section 9: Angles and Polygons
Hover over the Lesson: Angles in Triangles
Select and complete the Sub Lessons: Exterior Angle
Example
As you work through the lessons, complete the corresponding notes and diagrams below.
Exterior Angle
m
1+m
2+m
3 = ______ because the angles are interior angles of
a triangle.
m
4+m
3 = ______ because the angles form a __________ line
or a __________ angle.
Circle the portions of the two equations that are equal.
m
______ + m
- m
3=m
______ + m
______ + m
3
-m
3
3
Conclusion:
m
4=m
______ + m
______
Example
m
1 = ______ + ______
m
1 = ______
Also, m
1 + ______ = ______
- ______ - ______
m
1 = ______
Working In It:
For each triangle below:
Extend one side of the triangle.
Number the exterior angle and the interior angles.
Measure all four angles with a protractor and record the measurements within each diagram.
Write two equations that prove the measure of the exterior angle equals the sum of the interior angles
at the other vertices of the triangle.
Equation 1:
Equation 1:
Equation 2:
Equation 2:
Reflect And Connect:
Supply List: ruler, protractor, paper
Draw a triangle using a ruler on a separate sheet of paper.
Extend one side of the triangle to create an exterior angle.
Number the interior angles and the exterior angle.
Measure all four angles with a protractor and record the measurements below.
Write two equations that prove the measure of the exterior angle equals the sum of the interior angles
at the other vertices of the triangle.
Exchange papers with your partner. Check each other’s work. Discuss and correct any mistakes
before turning in your work to your teacher.
Build It. Draw It. Talk It. Write It. Now you OWN It!
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