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 50° and another is 60°, what is the measure of the exterior angle?

Back

The exterior angle is 110° (50° + 60°).

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

Solve for x: If one interior angle is 70° and the exterior angle is x, what is x?

Back

x = 70° + the other non-adjacent interior angle.

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 interior angle is 40° and another is 60°, what is the measure of the exterior angle?

Back

The exterior angle is 100° (40° + 60°).

Front

Solve for x: If the exterior angle is 105°, what are the measures of the two non-adjacent interior angles?

Back

The two non-adjacent interior angles must sum to 105°.

Front

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

Back

Exterior Angle = Interior Angle 1 + Interior Angle 2.