1. 3.4 parallel Lines and the Triangle Angle-Sum Theorem
12.0 Students find and use measures of interior and exterior angles of triangles to classify figures and solve problems
13.0 Students prove relationships between angles in polygons by using properties of complementary, supplementary, vertical, and exterior angles

2. Triangle Angle-Sum Theorem
The sum of the measures of the angles of a triangle is 180

3. Example #1

4. Example #2

5. Example #3

6. Classifying Different Triangles

7. Vocabulary
Exterior angle of a polygon – an angle formed by an side and an extension of an adjacent side

8. Vocabulary
Remote interior angle – two nonadjacent interior angles

9. Example #1 X 90
123°

10. Example #2 Z
57°
57°

11. Example #3
20°
35° X Y Z
43°

12. Assignment
Pg 150 #1-9, 20, 24, 26