1. 4.2 Angles of Triangles Then: You classified triangle by their side or angle measures. Now: 1. Apply the Triangle Angle-Sum Theorem. 2. Apply the Exterior Angle Theorem.

2. Theorem 4.1 Triangle Sum Theorem The sum of the measures of the angles of a triangle is 180.

3. Example 1 Find the measure of each numbered angle. a. b.

4. Example 1 c. The diagram shows the path of the softball in a drill developed by four players. Find the measure of each numbered angle. m  1 = m  2 = m  3 =

5. Example 1 d. Find the measure of each numbered angle. m  1 = m  2 =

6. Theorem 4.2 Exterior Angle Theorem The measure of an exterior angle of a triangle is equal to the sum of the measures of the two remote interior angles. http://www.wyzant.com/Help/Images/triangle_angle6.gif http://img.sparknotes.com/content/testprep/bookimgs/newsat/0004/exterior.gif

7. Example 2 a. Find the measure of each numbered angle. m  1 = m  2 =

8. Example 2 b. Find m  F.

9. Example 2 c. GARDENING Find the measure of  FLW in the fenced flower garden shown.

10. Triangle Angle-Sum Corollaries

11. Example 3 a. Find the measures of each numbered angle. m  1 = m  2 = m  3 = m  4 = m  5 =

12. Example 3 b. Find the measures of each numbered angle. m  1 = m  2 = m  3 =

13. Example 3 c. Find the measures of each numbered angle. m  1 = m  2 = m  3 = m  4 = m  5 =

14. 4.2 Assignment: p. 250-254 #12-22 evens, 23-30 all, 32, 33, 36, 38, 42,46, 52-58 evens