1. Proving Lines Parallel
Lesson 3-3
Proving Lines Parallel
SWBAT: Prove lines are parallel. STANDARD: NJSLS. G.CO.9

2. Proving Lines Parallel - Postulates & Theorems
Corresponding Angles Converse Postulate
If two lines are cut by a transversal and corresponding angles are congruent, then the lines are parallel.
SWBAT: Prove lines are parallel. STANDARD: NJSLS. G.CO.9

3. Proving Lines Parallel - Postulates &Theorems
Alt. Int. Angles Converse Thm
If two lines are cut by a transversal and alternate interior angles are congruent, then the lines are parallel.
SWBAT: Prove lines are parallel. STANDARD: NJSLS. G.CO.9

4. Proving Lines Parallel - Postulates &Theorems
Alt. Ext. Angles Converse Thm
If two lines are cut by a transversal and alternate exterior angles are congruent, then the lines are parallel.
SWBAT: Prove lines are parallel. STANDARD: NJSLS. G.CO.9

5. Proving Lines Parallel - Postulates &Theorems
Thm: Consecutive Int. Angles Converse
If two lines are cut by a transversal and consecutive interior angles are supplementary, then the lines are parallel.
SWBAT: Prove lines are parallel. STANDARD: NJSLS. G.CO.9

6. Proving Lines Parallel - Postulates &Theorems
Thm: Same Side Ext. Angles Converse
If two lines are cut by a transversal and same side exterior angles are supplementary, then the lines are parallel.
SWBAT: Prove lines are parallel. STANDARD: NJSLS. G.CO.9

7. Examples: Proving Lines Parallel
Find the value of x which will make lines a and lines b parallel. 2. 1. 3. 4.
Answers:
1. 20°
2. 50°
3. 90°
4. 20°
SWBAT: Prove lines are parallel. STANDARD: NJSLS. G.CO.9

8. Ways to Prove Two Lines Parallel
Show that corresponding angles are equal.
Show that alternative interior angles are equal.
Show that alternative exterior angles are equal.
Show that consecutive interior angles are supplementary.
Show that consecutive exterior angles are supplementary.
SWBAT: Prove lines are parallel. STANDARD: NJSLS. G.CO.9