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 one exterior angle measures 107°, what is the sum of the remote interior angles?

Back

The sum of the remote interior angles is 107°.

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

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, not the adjacent interior angle.

Front

If Angle A is 40° and Angle B is 60°, what is the measure of the exterior angle at Angle C?

Back

The measure of the exterior angle at Angle C is 100° (40° + 60°).

Front

How do you find the measure of an unknown angle using the Exterior Angle Theorem?

Back

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

Front

What is the measure of x if the remote interior angles are 50° and 60°?

Back

x = 110° (50° + 60°).

Front

If Angle X is 73° and Angle Y is 39°, what is the measure of the exterior angle?

Back

The measure of the exterior angle is 112° (73° + 39°).

Front

What is the sum of the angles in a triangle?

Back

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