1. Transversal
Definition: A line intersecting two or more other lines in a plane.
Picture:

2. Corresponding Angles
Definition: Angles that are in the same relative position.
Picture:

3. Corresponding Angles Conjecture
Conjecture: If two parallel lines are cut by a transversal, the corresponding angles are congruent.
Picture:

4. Alternate Interior Angles
Definition: On the “inside” and opposite side of the transversal.
Picture: ∠4 and ∠5 𝐨𝐫∠6 and ∠3

5. Alternate Interior Angles Conjecture
Conjecture: If two parallel lines are cut by a transversal, then the alternate interior angles are congruent. Picture:

6. Alternate Exterior Angles
Definition: On the “outside” and opposite side of the transversal.
Picture: ∠1 and ∠8 𝐨𝐫 ∠7 and ∠2

7. Alternate Exterior Angles Conjecture
Conjecture: If two parallel lines are cut by a transversal, then the alternate exterior angles are congruent. Picture:

8. Parallel Line Conjecture
Type of Angle
Special Feature
Corresponding Angles
Congruent
Alternate Interior Angles
Alternate Exterior Angles

9. Let’s Practice…
If ∠𝑀𝐿𝑁 = 105, what are the measures of the other 7 angles?

10. Let’s Practice…
If ∠3 = 97, what are the measures of the other 7 angles?

11. Let’s Practice…
If ∠ℎ = 60, what are the measures of the other 7 angles?