Interior and Exterior Angles of Triangles

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 two angles of a triangle are known, how can you find the third angle?

Back

Subtract the sum of the known angles from 180°.

Front

What are exterior angles of a triangle?

Back

Exterior angles are 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

Can a triangle have two obtuse angles?

Back

No, a triangle cannot have two obtuse angles because the sum of the angles would exceed 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 a triangle has angles measuring 45° and 65°, what is the measure of the third angle?

Back

The third angle measures 70°.

Front

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

Back

Each angle in an equilateral triangle measures 60°.