Triangles Sum Theorem & Exterior Angle Theorem

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°.

Front

What are the three types of angles based on their measures?

Back

1. Acute angles: less than 90° 2. Right angles: exactly 90° 3. Obtuse angles: greater than 90° and less than 180°.

Front

If one angle of a triangle is 90°, what type of triangle is it?

Back

It is a right triangle.

Front

What is the measure of each angle in an equilateral triangle?

Back

Each angle in an equilateral triangle measures 60°.

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 an exterior angle of a triangle?

Back

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

Front

What is the relationship between an exterior angle and the two opposite interior angles?

Back

The exterior angle is equal to the sum of the two opposite interior angles.

Front

If two angles of a triangle are 45° and 65°, what is the third angle?

Back

The third angle is 70° (180° - 45° - 65° = 70°).

Front

What is the measure of an angle that is complementary to a 50° angle?

Back

The complementary angle is 40° (90° - 50° = 40°).

Front

What is the measure of an angle that is supplementary to a 130° angle?

Back

The supplementary angle is 50° (180° - 130° = 50°).