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 A is an exterior angle, which angles are the remote interior angles?

Back

The remote interior angles are the two angles opposite to Angle A in the triangle.

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

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 C = 40° and Angle D = 60°, what is the measure of the exterior angle formed at Angle A?

Back

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

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 Angle W is an exterior angle, and Angle X = 50° and Angle Y = 70°, what is the measure of Angle W?

Back

Angle W = Angle X + Angle Y = 50° + 70° = 120°.

Front

Which equation can be used to find x if Angle A is an exterior angle?

Back

4x - 2 + 75 = 12x + 1.

Front

If Angle A = 120° and Angle B = 30°, what is the measure of Angle C?

Back

Angle C = 180° - (Angle A + Angle B) = 180° - (120° + 30°) = 30°.