1. Angles of Triangles Chapter 4, Section 2

2. Angle Sum Theorem The sum of angles in a triangle is 180 o. 1 2 3

3. Examples: Find the missing angles: ? 30 40 2882 68 ? ? ?

4. Third Angle Theorem If 2 angles in one triangle are congruent to 2 angles in a second triangle, then the third angles are also congruent. 62 58 60?

5. Exterior Angle Theorem The measure of an exterior angle is equal to the sum of the two remote interior angles R.I. Exterior The exterior angle is outside the triangle. Also, it forms a linear pair with one angle of the triangle. Remote interior angles are nonadjacent interior angles.

6. Examples 150 Find the measure of the exterior angle. ? 60 20 40 70 ? ? ? ?

7. Things to think about: The acute angles in a right triangle are always _______________. 42 3037 42 + 48 = 90 30 + 60 = 90 53 + 37 = 90 complementary

8. Things to think about: There can be no more than one ______________ or ____________ angle in a triangle. right obtuse NOT TRIANGLES!!