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 non-adjacent interior angles.

Front

If one exterior angle of a triangle measures 120 degrees, what is the sum of the two opposite interior angles?

Back

The sum of the two opposite interior angles is 120 degrees.

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 opposite interior angles, and it is supplementary to the adjacent interior angle.

Front

Calculate the value of x if the exterior angle is 40 degrees and one of the opposite interior angles is 25 degrees.

Back

x = 40 - 25 = 15 degrees.

Front

What is the measure of angle x if the exterior angle is 180 degrees?

Back

Angle x can be any value as the sum of the opposite interior angles must equal 180 degrees.

Front

If angle A = 50 degrees and angle B = 70 degrees, what is the measure of the exterior angle formed at vertex C?

Back

The exterior angle at vertex C is 50 + 70 = 120 degrees.

Front

What is the measure of angle 3x + 2 if it equals an exterior angle of 122 degrees?

Back

3x + 2 = 122; therefore, 3x = 120; x = 40 degrees.

Front

If angle 4y + 8 equals an exterior angle of 68 degrees, what is the value of y?

Back

4y + 8 = 68; therefore, 4y = 60; y = 15 degrees.

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 degrees.

Front

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

Back

To find the unknown angle, subtract the known opposite interior angle from the measure of the exterior angle.