1. 4.2 Angles of Triangles Objectives: *Apply the Angle Sum Theorem.
*Apply the Exterior Angle Theorem.
Mrs. S. Williams

2. Angle Sum Theorem
The sum of the measures of the angles of a triangle is 180.
W + X + Y = 180 X W Y

3. 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.
1 =
* and 3 are remote interior angles. 3 2 1

4. Ex. Angle Sum Theorem Find the missing angle measures. 82° 28° 1 2 63°

5. Ex. Exterior Angle Sum Theorem
Find the measure of each numbered angle in the figure. 3 2 1
120° 4 5
50°
56°
78°