Exterior Angle Theorem and Triangle Sum 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

What is the Triangle Sum Theorem?

Back

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

Front

If one angle of a triangle is 70°, what is the maximum possible measure of the other two angles?

Back

The maximum possible measure of the other two angles is 110° (since 180° - 70° = 110°).

Front

If two angles of a triangle are 45° and 55°, what is the measure of the third angle?

Back

The third angle measures 80° (since 180° - 45° - 55° = 80°).

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

Back

x = 5.

Front

What is the measure of an exterior angle if the two opposite interior angles are 30° and 50°?

Back

The measure of the exterior angle is 80° (30° + 50° = 80°).

Front

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

Back

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

Front

Back

x = 110°.

Front

If one angle of a triangle is 90°, what can you say about the other two angles?

Back

The other two angles must sum to 90° (since the total must be 180°).