Angles in Triangles

Front

What is the Triangle Sum Theorem?

Back

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

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°.

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 acute angle?

Back

An acute angle is an angle that measures less than 90°.

Front

What is an obtuse angle?

Back

An obtuse angle is an angle that measures more than 90° but less than 180°.

Front

What is a right angle?

Back

A right angle is an angle that measures exactly 90°.

Front

If two angles in a triangle are 30° and 60°, what is the measure of the third angle?

Back

The third angle measures 90°.

Front

What is the relationship between the angles in a triangle and the exterior angle?

Back

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

Front

If one angle of a triangle is 110°, what is the maximum measure of the other two angles?

Back

The maximum measure of the other two angles is 70° (since they must sum to 70°).