1. Why do triangle angles always sum to 180°?

2. In this lesson you will learn about the interior angles of triangles by looking at their properties.

3. Let’s Review The three angles of a triangle always sum to 180°. 98 + 42 + 40 = 18084 + 69 + 27 = 180111 + 46+ 23 = 18090 + 68 + 22 = 180

4. A line that passes through parallel lines is called a transversal.

5. Transversals create special angle properties. Alternate Exterior AnglesCorresponding Angles Alternate Interior Angles

6. Core Lesson Triangles share many of these angle relationships. 1 1 2 3 3

7. Find the missing angle measurement. x 89 + 68 = 157 180-157 = 23 x = 23°

8. In this lesson you have learned about the interior angles of triangles by looking at their properties.