Triangle Theorem Sum & Exterior Theorem

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

What is the Exterior Angle Theorem?

Back

The Exterior Angle Theorem states that the measure of an exterior angle is equal to the sum of the measures of the two opposite interior angles.

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 an unknown angle in a triangle?

Back

Subtract the sum of the known angles from 180°.

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°.

Front

What is the relationship between the angles in a triangle?

Back

The angles in a triangle are related such that their sum is always 180°.

Front

What is a scalene triangle?

Back

A scalene triangle is a triangle with all sides of different lengths and all angles of different measures.

Front

What is an isosceles triangle?

Back

An isosceles triangle is a triangle with at least two sides of equal length and at least two angles of equal measure.

Front

If one angle of a triangle is 70° and another is 40°, what is the measure of the third angle?

Back

The third angle measures 70°.