Exterior Angles Theorem Flashcard

Front

What is the Exterior Angles Theorem?

Back

The Exterior Angles 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

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 95° and another is 66°, what is the measure of the third angle?

Back

The third angle is 19° (180° - 95° - 66° = 19°).

Front

What is an exterior angle?

Back

An exterior angle is formed by one side of a triangle and the extension of an adjacent side.

Front

If ∠a = 40° and ∠b = 60°, what is the measure of ∠d?

Back

∠d = ∠a + ∠b = 40° + 60° = 100°.

Front

How do you find the measure of a missing angle in a triangle?

Back

Subtract the sum of the known angles from 180°.

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.

Front

If ∠a = 30° and ∠b = 50°, what is the measure of ∠d?

Back

∠d = ∠a + ∠b = 30° + 50° = 80°.

Front

What is the Triangle Sum Theorem?

Back

The Triangle Sum Theorem states that the sum of the angles in a triangle is always 180°.

Front

If ∠a = 45° and ∠b = 45°, what is the measure of the exterior angle ∠d?

Back

∠d = ∠a + ∠b = 45° + 45° = 90°.