1.  4.1 Classifying Triangles

2. Example 1

4. Example 2

5. Example 3

6. You Try It…

7. 4.2 Angle Measures of Triangles

8. Triangle Sum Theorem  The sum of the measures of the angles in a triangle is 180 degrees.

9. Example 1

10. Corollary to Triangle Sum Theorem The acute angles of a right triangle are complementary.

11. Vocabulary

12. Exterior Angle Theorem The measure of an exterior angle of a triangle is equal to the sum of the measures of the two nonadjacent interior angles.

13. Example 2

14. You Try It… Find the measure of the exterior angle:

15. A little bit trickier now..