# 2.6 Special Angles on Parallel Lines

## Investigation #1

## Use this figure for Investigation #1

## Observation

Which of the following statements is always true about corresponding pairs of angles, like and ?

Which of the following statements is always true about alternate exterior pairs of angles, like and ?

Which of the following statements is always true about alternate interior pairs of angles, like and ?

Which of the following statements is always true about same side interior pairs of angles, like and ?

Which of the following statements is always true about same side exterior pairs of angles, like and ?

## C-3 Parallel Lines Conjecture

If two parallel lines are cut by a transversal, then corresponding angles are _____, alternate interior angles are _____, and alternate exterior angles are _____.

## Investigation #2

## Observation

Which of the following statements is true about the slopes of the lines cut by transversal CB?

## C-4 Converse of the Parallel Lines Conjecture

If two lines are cut by a transversal to form pairs of congruent corresponding angles, congruent alternate interior angles, or congruent alternate exterior angles, then the lines are _____.