1. Write an equation in slope-intercept form of the line having the given slope and y-intercept: m: –4, b: 3 m: 3, b: –8 m: 3 7 , (0, 1) m: – 2 5 , (0, –6)
Problem of the Day

2. Section 3-5 Proving Lines Parallel

3. Then
Now
Objectives
You used slopes to identify parallel and perpendicular lines.
Recognize angle pairs that occur with parallel lines.
Prove the two lines are parallel.

4. Common Core State Standards
Content Standards
G.CO.9 – Prove theorems about lines and angles.
Mathematical Practices
1) Make sense of problems and persevere in solving them.
3) Construct viable arguments and critique the reasoning of others.
Common Core State Standards

5. Converse of Corresponding Angles Postulate

6. Proving Lines Parallel

7. Given the following information, determine which lines, if any, are parallel. State the postulate or theorem that justifies your answer. ∠2 ≅ ∠8 ∠3 ≅ ∠11 ∠12 ≅ ∠14 ∠1 ≅ ∠15 m∠8 + ∠13 = 180 ∠8 ≅ ∠6
Example 1

8. Given the following information, determine which lines, if any, are parallel. State the postulate or theorem that justifies your answer. ∠3 ≅ ∠7 ∠9 ≅ ∠11 ∠2 ≅ ∠16 m∠5 + ∠12 = 180
Example 1

9. Given the following information, determine which lines, if any, are parallel. State the postulate or theorem that justifies your answer. ∠CBF ≅ ∠GFH ∠EFB ≅ ∠FBC ∠ACD ≅ ∠KBF m∠BCG + ∠FGC = 180
Example 1

10. Example 3 Given: ∠5 ≅ ∠15, ∠1 ≅ ∠5 Prove: r ∥ s, ℓ ∥ m Statements
Reasons
1. ∠5 ≅ ∠15
2. ∠15 ≅ ∠13
3. ∠5 ≅ ∠13
4. r ∥ s
5. ____________________________
6. ____________________________
1. ___________________________________
2. ___________________________________
3. ___________________________________
4. ___________________________________
5. Given
6. If corr s are ≅, then lines ∥.

11. p.210 #8 – 15, 48 – 50, 57
Homework