1. Lesson 3-5 Proving Lines Parallel

2. Concept

5. Example 1 Identify Parallel Lines A. Given  1   3, is it possible to prove that any of the lines shown are parallel? If so, state the postulate or theorem that justifies your answer.

6. Example 1 Identify Parallel Lines A. Given  1   3, is it possible to prove that any of the lines shown are parallel? If so, state the postulate or theorem that justifies your answer. Answer: Yes, because <1 & <3 are corresponding ang

7. Example 1 Identify Parallel Lines B. Given m  1 = 103 and m  4 = 100, is it possible to prove that any of the lines shown are parallel? If so, state the postulate or theorem that justifies your answer.

8. Example 1 Identify Parallel Lines B. Given m  1 = 103 and m  4 = 100, is it possible to prove that any of the lines shown are parallel? If so, state the postulate or theorem that justifies your answer. Answer: NO, because if lines a and c were II then <1 & <4 would be congruent; AIA

9. Example 1 A.Yes; ℓ ║ n B.Yes; m ║ n C.Yes; ℓ ║ m D.It is not possible to prove any of the lines parallel. A. Given  1   5, is it possible to prove that any of the lines shown are parallel?

10. Example 1 A.Yes; ℓ ║ n B.Yes; m ║ n C.Yes; ℓ ║ m D.It is not possible to prove any of the lines parallel. B. Given m  4 = 105 and m  5 = 70, is it possible to prove that any of the lines shown are parallel?

11. Example 2 Find m  ZYN so that ||. Show your work. Use Angle Relationships

12. Example 2 Use Angle Relationships

13. Example 2 ALGEBRA Find x so that ||. A.x = 60 B.x = 9 C.x = 12 D.x = 12

14. Example 3 A.The two horizontal lines are parallel. B.The two vertical lines are parallel. C.The vertical lines are perpendicular to the horizontal lines. D.All of these statements are true. GAMES In the game Tic-Tac-Toe, four lines intersect to form a square with four right angles in the middle of the grid. Is it possible to prove any of the lines parallel or perpendicular? Choose the best answer.