4.7 Triangle Angle Sum and Exterior Angle

Front

What is the Triangle Angle Sum Theorem?

Back

The Triangle Angle Sum Theorem states that 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 the angles of a triangle are 40 degrees and 60 degrees, what is the third angle?

Back

The third angle is 80 degrees (180 - 40 - 60 = 80).

Front

What type of triangle has all sides of equal length?

Back

An equilateral triangle.

Front

What is an isosceles triangle?

Back

An isosceles triangle has at least two sides that are equal in length.

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

If a triangle has angles measuring 30 degrees and 50 degrees, what is the measure of the third angle?

Back

The third angle measures 100 degrees (180 - 30 - 50 = 100).

Front

What is the formula for finding the sum of the angles in a triangle?

Back

The sum of the angles in a triangle is always 180 degrees.