Exterior Angle Theorem

Front

What is the Exterior Angle Theorem?

Back

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

Front

What are remote interior angles?

Back

Remote interior angles are the two angles inside a triangle that are not adjacent to a given exterior angle.

Front

If Angle W is an exterior angle, which angles are the remote interior angles?

Back

The remote interior angles to Angle W are the two angles inside the triangle that do not share a vertex with Angle W.

Front

How do you find the measure of an exterior angle?

Back

To find the measure of an exterior angle, add the measures of the two remote interior angles.

Front

If Angle X = 40° and Angle Y = 60°, what is the measure of the exterior angle formed at their vertex?

Back

The measure of the exterior angle is 40° + 60° = 100°.

Front

What is the relationship between an exterior angle and its adjacent interior angle?

Back

The exterior angle is equal to the sum of the two remote interior angles, and it is supplementary to the adjacent interior angle.

Front

If Angle A is 50° and Angle B is 70°, what is the measure of the exterior angle at their vertex?

Back

The measure of the exterior angle is 50° + 70° = 120°.

Front

What is the sum of the interior angles of a triangle?

Back

The sum of the interior angles of a triangle is always 180°.

Front

If one interior angle of a triangle is 90°, what can you say about the other two angles?

Back

The other two angles must sum to 90° since the total must equal 180°.

Front

In a triangle, if one exterior angle measures 130°, what are the measures of the remote interior angles?

Back

The remote interior angles must sum to 130°.