## triangle-proof.gif - Section 1: Introducing Today's Work

triangle-proof.gif

# Walking Around a Triangle

Unit 5: Lines, Angles, and Algebraic Reasoning
Lesson 8 of 16

## Big Idea: In this investigation we open with AA criterion for triangles and help students discover that the exterior angles of a triangle (and any polygon) must always add to 360.

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2 teachers like this lesson
Standards:
Subject(s):
Math, Proofs, Geometry, exterior angle, transversals, protractor, interior angles, 8th grade
55 minutes

### Shaun Errichiello

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