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 m∠A = 40° and m∠B = 60°, what is m∠C if it is the exterior angle?

Back

m∠C = m∠A + m∠B = 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 opposite interior angles, while the adjacent interior angle is supplementary to the exterior angle.

Front

Solve for x: m∠1 + m∠2 = x, where m∠1 = 30° and m∠2 = 50°.

Back

x = 30° + 50° = 80°.

Front

If an exterior angle measures 120°, what is the sum of the two opposite interior angles?

Back

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

Front

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

Back

The measure of an exterior angle can be found using the formula: m∠Exterior = m∠Interior1 + m∠Interior2.

Front

If m∠A = 70° and m∠B = 40°, what is the measure of the exterior angle at vertex C?

Back

m∠C = m∠A + m∠B = 70° + 40° = 110°.

Front

Solve for x: If m∠A = 45° and m∠B = 55°, find x where x is the exterior angle.

Back

x = 45° + 55° = 100°.

Front

What do you call the angle formed outside a triangle when one side is extended?

Back

That angle is called an exterior angle.

Front

If m∠D = 30° and m∠E = 50°, what is the measure of the exterior angle at vertex F?

Back

m∠F = m∠D + m∠E = 30° + 50° = 80°.