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 interior angle of a triangle is 40° and another is 70°, what is the measure of the exterior angle?

Back

The exterior angle is 110° (40° + 70°).

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, not the adjacent one.

Front

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

Back

Add the measures of the two non-adjacent interior angles to find the measure of the exterior angle.

Front

If an exterior angle measures 130°, what are the possible measures of the two non-adjacent interior angles?

Back

The sum of the two non-adjacent interior angles must equal 130°.

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 one angle of a triangle is 60° and another is 50°, what is the measure of the third angle?

Back

The third angle measures 70° (180° - 60° - 50°).

Front

How can you use the Exterior Angle Theorem to solve for an unknown angle in a triangle?

Back

Identify the known interior angles, add them together, and set that sum equal to the exterior angle.

Front

What is an example of an exterior angle in a triangle?

Back

An exterior angle is formed when one side of the triangle is extended, creating an angle outside the triangle.

Front

If an exterior angle is 95°, what are the measures of the two non-adjacent interior angles?

Back

The sum of the two non-adjacent interior angles must equal 95°.