Define and use the interior angle sum theorem for triangles.
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Students have experience working with triangles and angle measurements from seventh grade when they investigated unique triangles. While students may know that the angles in a triangle add up to 180°, in this lesson they have the chance to prove this fact using parallel line angle relationships.
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Given that $${\overleftrightarrow{DE} \parallel \overleftrightarrow{AC}}$$ in the diagram below, prove that $${a+b+c=180}$$.
A Triangle's Interior Angles, accessed on Aug. 10, 2017, 9:48 a.m., is licensed by Illustrative Mathematics under either the CC BY 4.0 or CC BY-NC-SA 4.0. For further information, contact Illustrative Mathematics.
Modified by The Match Foundation, Inc.In the picture below, lines $$l$$ and $$m$$ are parallel. The measure of $$\angle PAX$$ is $${31^{\circ}}$$, and the measure of $$\angle PBY$$ is $${54^{\circ}}$$.
What is the measure of $$\angle APB$$?
Find the Missing Angle, accessed on Oct. 13, 2017, 4:22 p.m., is licensed by Illustrative Mathematics under either the CC BY 4.0 or CC BY-NC-SA 4.0. For further information, contact Illustrative Mathematics.
Determine the angle measures of each interior angle in the triangle.
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The following resources include problems and activities aligned to the objective of the lesson that can be used to create your own problem set.
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In the diagram below, $${L_1 \parallel L_2}$$ and $${L_3 \parallel L_4}$$. Use the diagram to answer the questions that follow.
Grade 8 Mathematics > Module 2 > Topic C > Lesson 13 of the New York State Common Core Mathematics Curriculum from EngageNY and Great Minds. © 2015 Great Minds. Licensed by EngageNY of the New York State Education Department under the CC BY-NC-SA 3.0 US license. Accessed Dec. 2, 2016, 5:15 p.m..
Modified by The Match Foundation, Inc.?