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# 1.B: Parallel Lines and Transversals

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## Overview

The purpose of this lesson is to learn how angles are related to each other on a set of two parallel lines cut by a transversal.

This lesson will address the following CCRS Standard(s) for Geometry:

• 7.G.5: Use facts about supplementary, complementary, vertical, and adjacent angles in a multi-step problem to write and solve simple equations for an unknown angle in a figure
• 8.G.5: Use informal arguments to establish facts about the angle sum and exterior angles of triangles, above the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles. For example, arrange three copies of the same triangle so that the sum of the three angles appears to form a line, and give an argument in terms of transversals why this is so

## Directions

1. Take notes while watching videos below
2. Go to http://wamap.org and log into our course to complete assignment 1.B with 80% or better.

### Watch

Parallel Lines and Transversals [9:40]

### Do

Complete assignment 1.B with 80% or better at http://wamap.org

## Summary

In this lesson we have learned:

• If two parallel lines are cut by a transversal, all the acute angles are congruent to each other and the all the obtuse angles are congruent to each other.
• If to parallel lines are cut by a transversal, then any of the acute angles will be supplementary to any of the obtuse angles.