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

Back

180 degrees.

Front

If one angle of a triangle is 50°, what is the maximum measure of an exterior angle at that vertex?

Back

The maximum measure of the exterior angle is 130° (180° - 50°).

Front

What are remote interior angles in relation to an exterior angle?

Back

Remote interior angles are the two non-adjacent interior angles of a triangle that are opposite to the exterior angle.

Front

If angle A is 30° and angle B is 70°, what is the measure of the exterior angle at vertex C?

Back

The exterior angle at vertex C is 100° (30° + 70°).

Front

How do you find the measure of an exterior angle if you know the two remote interior angles?

Back

Add the measures of the two remote interior angles together.

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 W is 40°, what are the measures of the remote interior angles?

Back

If angle W is 40°, the remote interior angles are the other two angles in the triangle, which can be found using the Exterior Angle Theorem.

Front

What is the formula to calculate the measure of an exterior angle?

Back

Measure of exterior angle = Measure of angle 1 + Measure of angle 2 (where angle 1 and angle 2 are the remote interior angles).

Front

In a triangle, if one angle measures 90°, what can you say about the other two angles?

Back

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