1. Chapter 3: Parallel and Perpendicular Lines
Lesson 2: Angles and Parallel Lines

2. If two parallel lines are cut by a transversal, then… (see graphic organizer)
the alternate interior angles are congruent
the consecutive interior angles are supplementary
the alternate exterior angles are congruent
the corresponding angles are congruent
In a plane, if a line is perpendicular to one of the two parallel lines, then it is also perpendicular to the other line.

3. Examples
A. In the figure, m11 = 51. Find m15. Tell which postulates (or theorems) you used.
B. In the figure, m11 = 51. Find m16. Tell which postulates (or theorems) you used.

4. Examples A. In the figure, a || b and m20 = 142. Find m22.
B. In the figure, a || b and m20 = 142. Find m23.

5. Examples A. ALGEBRA If m5 = 2x – 10, and m7 = x + 15, find x.
B. ALGEBRA If m4 = 4(y – 25), and m8 = 4y, find y.

6. Examples
ALGEBRA If m1 = 9x + 6, m2 = 2(5x – 3), and m3 = 5y + 14, find x.
B. ALGEBRA If m1 = 9x + 6, m2 = 2(5x – 3), and m3 = 5y + 14, find y.