Chapter 3 Section 3-1: Properties of Parallel Lines Goal 2.02: Apply properties, definitions, and theorems of angles and lines to solve problems and write problems and write proofs.

Turn in Cumulative Review Check Skills: p 115 (1-6)

Essential Questions How are angles formed by 2 lines and a transversal identified? How are the properties of parallel lines used to determine angle measure?

Transversal a line that intersects two or more coplanar lines in different points

Alternate Interior Angles (alt. int.  ‘s) two nonadjacent interior angles on opposite side of the transversal

Same-Side Interior Angles Also called consecutive angles (s-s int.  ‘s) two interior angles on the same side of the transversal

Corresponding Angles (corres.  ‘s) two angles in corresponding positions relative to the two lines

Examples, p 118 5) 7) Together: p 118-119 (6,8)

Examples 2 and 3 SPQ and PSR Together: 2, 4

Theorem about Parallel Planes If two parallel planes are cut by a third plane, then the lines of intersection are parallel.

Example Use # 9 for 4th property of: if 2 parallel lines are cut by a transversal then …. P. 119 11. 13. 15.

P 120 Two lines and a transversal form how many pairs of the following P 120 Two lines and a transversal form how many pairs of the following? 19 Alternate interior angles 20 corresponding angles 21 same-side interior angles 22 vertical angles

Postulate and Theorems about angles formed by 2 Parallel lines and a transversal If two parallel lines are cut by a transversal, then the corresponding angles are congruent. (post) If two parallel lines are cut by a transversal, then alternate interior angles are congruent. If two parallel lines are cut by a transversal, then same-side interior angles are supplementary. If a transversal is perpendicular to one of two parallel lines, then it is perpendicular to the other also.  

Practice With a partner: p 119 (12- 16 even) p 120 (23-25 all) Go over. Individually: Practice 3-1 Worksheet

Summarize List the 4 things you know if 2 parallel lines are cut by a transversal. 1. 2. 3. 4. Standardized Test Prep: p. 121 (37-41 all)

Homework Mixed Review: p 121 (42- 50 all) Worksheet: Definitions worksheet Review