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8.G.5 Reteaching

At the end of this lesson, students will be able to...

1: Formulate arguments to establish facts about the interior and exterior angles of a triangle 2: Formulate arguments about the angles created when parallel lines are cut by a transversal

Part 1

Explore the figure below by dragging movable points, and record at least 6 observations.

What are the six (or more) observations you made about the graphic above? Answer in a numbered list.

Part 2

Match types of angles to their properties

Part 3: Angles in Triangles

Task: 1. Explore the given triangle. Make at least 2 observations about the angles emphasized. 2. Use your observations to make a conjecture about the relationship between interior and exterior triangle angles. 3. Open a new GeoGebra Geometry worksheet. Build at least one triangle and use the tools to test your theory from question 2. (Repeat steps 1-3 as needed) 4. Write a rule that is always true about the interior and exterior angles of a triangle. Share your rule and a screenshot of your work to the Padlet.

Share your work using a screenshot from Question 3 and your rule from Question 4 to this Padlet below.

Extension Activity

1. Prove the Triangle Exterior Angle Theorem algebraically.