1. RECALL
A transversal is a line that intersects two coplanar lines at two distinct points. The diagram shows the eight angles formed by a transversal t and two lines l and m.

2. RECALL
Pairs of the eight angles have special names as suggested by their positions.
Angles 1 and 5 are examples of corresponding angles.
Angles 1 and 8 are examples of alternate exterior angles.
Angles 3 and 6 are examples of alternate interior angles.
Angles 3 and 5 are examples of same-side interior angles.

3. 3-1 Properties of Parallel Lines
Goal 1: To identify angles formed by two lines and a transversal
Goal 2: To prove and use properties of parallel lines

5. Please do not proceed until told to do so!

6. We’re now going to explore the relationships among these special angle pairs when the two lines being intersected by a transversal happen to be parallel to one another.
Activity
Open GSP 4.06 from the start menu.
Follow along as we complete the Properties of Parallel Lines GSP activity steps 1-4 as a class.
With a partner read and complete, up to, but not including step 7. Answer all questions on the sheet.

7. Theorems
Complete the following statements based upon your observations from the lesson:
If two parallel lines are cut by a transversal, then
corresponding angles are _____________________.
alternate interior angles are _____________________.
same-side interior angles are _____________________.
alternate exterior angles are _____________________.

8. Classwork: Practice Worksheet 3-1
Assignment: p. 118 #1-26