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 degrees.

Front

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

Back

It is a right triangle.

Front

What is an exterior angle of a triangle?

Back

An exterior angle is 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

If two angles of a triangle are 25 degrees and 55 degrees, what is the measure of the third angle?

Back

The third angle is 100 degrees (180 - 25 - 55 = 100).

Front

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

Back

Each angle in an equilateral triangle measures 60 degrees.

Front

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

Back

Subtract the sum of the known angles from 180 degrees.

Front

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

Back

Exterior angle = Interior angle 1 + Interior angle 2.

Front

If one angle of a triangle is 70 degrees and another is 40 degrees, what is the value of x in the equation x + 70 + 40 = 180?

Back

x = 70 degrees.

Front

What is the definition of complementary angles?

Back

Complementary angles are two angles whose measures add up to 90 degrees.