Interior and Exterior Angles of Triangles

Front

What is an interior angle of a triangle?

Back

An interior angle of a triangle is formed by two sides of the triangle that meet at a vertex, and it is located inside the triangle.

Front

What is an exterior angle of a triangle?

Back

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

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 degrees.

Front

If one interior angle of a triangle is 60 degrees and another is 70 degrees, what is the measure of the third angle?

Back

The third angle measures 50 degrees (180 - 60 - 70 = 50).

Front

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

Back

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

Front

If an exterior angle measures 120 degrees, what is the sum of the two opposite interior angles?

Back

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

Front

How do you find the measure of an unknown interior angle in a triangle?

Back

To find an unknown interior angle, subtract the sum of the known angles from 180 degrees.

Front

What is the formula for calculating the measure of an exterior angle?

Back

The measure of an exterior angle is equal to the sum of the two non-adjacent interior angles.

Front

If a triangle has angles measuring 45 degrees and 55 degrees, what is the measure of the third angle?

Back

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

Front

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

Back

Each interior angle in an equilateral triangle measures 60 degrees.