1. Warm Up Give the complement of each angle. 1. 80° 2. 64° 3. 15° 4. 48 ° 10° 26° 75° 42°

2. When two parallel lines are cut by a third line, the third line is called the transversal.

3. 8.4 Classifying Pairs of Lines 6.2.4 I will learn to classify pairs of lines

4. Vocabulary parallel lines perpendicular lines skew lines

5. Intersecting lines are lines that cross at one common point. Parallel lines are lines in the same plane that never intersect. Line YZ intersects line WX. YZ intersects WX. Line AB is parallel to line ML. AB ML. Y W Z X B A M L The red arrows on the lines show that the lines are parallel. Reading Math

6. Perpendicular lines intersect to form 90° angles, or right angles. Line RS is perpendicular to line TU. RS TU. S R TU Skew lines are lines that lie in different planes. They are neither parallel nor intersecting. Line AB and line ML are skew. AB and ML are skew. M L A B

7. The handrails on an escalator are in the same plane. What type of line relationship do they represent? The handrails are in the same plane and do not intersect. The lines are parallel.

8. The roads are in the same plane. What type of line relationship do they represent? The lines cross at one common point. The lines are intersecting.

9. Classify each pair of lines. The lines are in different planes and are not parallel or intersecting. They are skew.