1. Angles Outside the Triangle 4-1B What are remote interior angles? What is the relationship between an exterior angle and the remote interior angles?

2. Exterior Angle An exterior angle is formed by extending one of the side of the triangle. Exterior angle

3. Adjacent Interior Angle… The interior angle in a linear pair with an exterior angle. Adjacent interior angle An exterior angle

4. Remote Interior Angles The two angles that are away from the exterior angle. Exterior angle Remote interior angle

5. Try It 1.Name the exterior angles in the figure. 2. Name the remote interior angles for angle 3. 1 2 3 4 5 6

6. What’s My Angle? You will need paper, a straight edge and a protractor. You will draw one of the following as instructed: Equilateral triangleIsosceles triangle Right triangleScalene Triangle Obtuse Triangle Draw an extension on one side and measure the exterior angle and the three interior angles.

7. Complete the Table. 83°40° 84°148° 71°54° 12 3 4

8. Exterior Angle Theorem The measure of an exterior angle of a triangle is equal to the sum of the measures of its remote interior angles.

9. Exterior Angle Inequality Theorem The measure of an exterior angle of a triangle is greater than the measure of either of its remote interior angles.

10. Theorems about Angles in Special Triangles Each angle of an equilateral triangle measures 60°. The acute angles of a right triangle are complementary.

11. What are remote interior angles? The two angles that are away from the exterior angle. What is the relationship between an exterior angle and the remote interior angles? The measure of an exterior angle of a triangle is equal to the sum of the measures of its remote interior angles.

12. Assignment 4-1B Page 250, 1-9, 13-15, 19-24