# Lesson 3 3 Proving Lines Parallel SWBAT Prove

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

Proving Lines Parallel - Postulates & Theorems Corresponding Angles Converse Postulate l 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 2

Proving Lines Parallel - Postulates &Theorems Alt. Int. Angles Converse Thm l 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 3

Proving Lines Parallel - Postulates &Theorems Alt. Ext. Angles Converse Thm l 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 4

Proving Lines Parallel - Postulates &Theorems Thm: Consecutive Int. Angles Converse l 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 5

Proving Lines Parallel - Postulates &Theorems Thm: Same Side Ext. Angles Converse l 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 6

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

Ways to Prove Two Lines Parallel l l 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 8

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