✓ Lesson Check

Do you know HOW?

State the theorem or postulate that proves a || b.

1. 
2. 
3. What is the value of y for which a || b eh vertical linevertical line b  in Exercise 2?

Do you UNDERSTAND?

4. Explain how you know when to use the Alternate Interior Angles Theorem and when to use the Converse of the Alternate Interior Angles Theorem.
5. Compare and Contrast How are flow proofs and two-column proofs alike? How are they different?

6. Error Analysis A classmate says that A B ↔ || D C ↔ modified eh b with left right arrow above , vertical linevertical line , modified d c with left right arrow above  based on the diagram below. Explain your classmate's error.