Parallel Lines, Transversals, and Angles 3-4B

1
Parallel Lines, Transversals, and Angles 3-4B

• What special relationships happen when a
  transversal crosses parallel lines?

2
Parallel Crossing

• You will need a sheet of paper, a straightedge
  and a protractor.
• Draw two parallel lines.
• Draw a transversal through the two lines.
• Measure all the angles.
• Do you see any patterns?

3
Try It
p
72
2
1
q
3
4
6
5
7
8
4
Postulate

• If parallel lines are cut by a transversal, then
  the alternate interior angles are congruent.

x
x
x
x
5
Theorems

• If parallel lines are cut by a transversal, then
  the corresponding angles are congruent.

6
Theorems

• If parallel lines are cut by a transversal, then
  the alternate exterior angles are congruent.

7
Theorems

• If parallel lines are cut by a transversal, then
  same-side interior angles are supplementary.

8

• What special relationships happen when a
  transversal crosses parallel lines?
• If parallel lines are cut by a transversal, then
  the alternate interior angles are congruent.
• If parallel lines are cut by a transversal, then
  the corresponding angles are congruent.
• If parallel lines are cut by a transversal, then
  the alternate exterior angles are congruent.
• If parallel lines are cut by a transversal, then
  same-side interior angles are supplementary.

9
Assignment 3-4B

• p. 223, 1-2, 5-6, 10-12, 15-17