Interior and Exterior Angles of Triangles

Front

What is an interior angle of a triangle?

Back

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

What is an exterior angle of a triangle?

Back

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

Front

What is the relationship between an exterior angle and the interior angles of a triangle?

Back

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

Front

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

Back

It is a right triangle.

Front

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

Back

Subtract the sum of the known interior angles from 180 degrees.

Front

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

Back

Each angle in an equilateral triangle measures 60 degrees.

Front

If two angles of a triangle are 45 degrees and 75 degrees, what is the measure of the third angle?

Back

The third angle measures 60 degrees (180 - 45 - 75 = 60).

Front

What is the formula for calculating the exterior angle of a triangle?

Back

Exterior angle = Interior angle 1 + Interior angle 2.

Front

In a triangle, if one angle measures 116 degrees, what can you say about the other two angles?

Back

The other two angles must be acute (less than 90 degrees) and their sum must be 64 degrees (180 - 116 = 64).