Geometry Agenda 1. ENTRANCE 2. go over practice 3. 3-2 Proving Lines Parallel 4. Practice Assignment 5. EXIT

Practice

Transitive Property If a=b and b=c, then a=c. If and , then . If 12 and 23, then 13.

Example #7 Given: a||b Prove: 13 1. a||b 2. 14 3. 43 4. 13

Example #8 Given: a||b Prove: 1 supple 2 1. a||b 2. m2+m3=180 3. 31 4. m2+m1=180 5. 1 supple 2

3-2 Proving ________ Parallel Chapter 3 3-2 Proving ________ Parallel

Flowchart Proof Proof with statements in boxes and reasons below them. ex: Given: 2x – 7 = 3 Prove: x = 5

Postulate 3-2, Theorems 3-3 and 3-4 If two lines and a transversal form: Corresponding angles that are congruent Alternate interior angles that are congruent Same-side interior angles that are supplementary then the two lines are __________.

Theorem 3-5 If two lines are parallel to the same line, then they are parallel to each other. x||y and y||z therefore, x||z

Theorem 3-6 In a plane, if two lines are ___________ to the same line, then they are parallel to each other. gh and hj therefore, g||j

Example #1 Which lines (if any) must be parallel if: a. 26 c. 10 supple 11 d. 38

Example #2 Find x for which m||n.

Example #3 Find x for which a||b.

Example #4 Find x for which p||q.

Example #5 Given: 32 Prove: m||n

Example #6 Given: at bt Prove: a||b (prove Thm 3-6)

Practice WB 3-2 # 2-13 EXIT