1. The Triangle Sum Theorem

2.  The sum of the measures of the angles of a triangle are equal to 180 degrees. 1 2 3 4 5 < 5 = < 3 and < 4= < 1 because alternate interior angles are congruent. Since <1+ < 2+ < 3=180 degrees then the sum of the interior angles is 180.

3. Definition of Remote Interior Angles  An Interior angle of a triangle that is not adjacent to a given exterior angle.  Ex. 1 2 34 Angles 1 and 2 are remote Interior angles of angle 4.

4. Exterior Angle Theorem  The Exterior Angle equals the sum of the two remote interior angles. (remote interior angles don’t touch the exterior angle). 50° 70° 1 2 3 4 < 4 equals the sum of <1 +<2. 50+70= 120 so <4= 120°

9.  Homework  p.189(15-27) all  you MUST copy the pictures!!!!!!