GeoGebra Classroom

# 2.6 Special Angles on Parallel Lines

## Investigation #1

Line AD is parallel to Line FG in the figure below. 1. Use the angle tool to measure all 8 angles in the figure below. 2. Click and drag point C to change the angle measures. 3. Complete the questions below the figure based on your observations.

## Observation

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

Select all that apply
• A
• B
• C
• D

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

Select all that apply
• A
• B
• C
• D

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

Select all that apply
• A
• B
• C
• D

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

Select all that apply
• A
• B
• C
• D

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

Select all that apply
• A
• B
• C
• D

## 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 _____.

Select all that apply
• A
• B
• C
• D

## Investigation #2

In this investigation, we will create the congruent angles first, then observe the relationship between the lines we create. 1. Change the angle tool to an angle with given size tool. 2. Click B, then D, then change the angle measure to 65. Change the direction to clockwise before clicking ok. 3. Use the line tool to create line B'D. 4. Change the angle with given size tool to the slope tool. 5. Click lines B'D and AB to measure the slopes. 6. Complete the questions below based on your observations.

## Observation

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

Select all that apply
• A
• B
• C
• D

## 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 _____.

Select all that apply
• A
• B
• C