Triangle Angle Sum and Exterior Angle Theorem

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

What is the Exterior Angle Theorem?

Back

The Exterior Angle Theorem states that the measure of an exterior angle of a triangle is equal to the sum of the measures of the two non-adjacent interior angles.

Front

If one angle of a triangle is 50 degrees and another is 60 degrees, what is the measure of the third angle?

Back

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

Front

What is the measure of an exterior angle if the two non-adjacent interior angles are 40 degrees and 50 degrees?

Back

The exterior angle measures 90 degrees (40 + 50 = 90).

Front

In a triangle, if one angle measures 90 degrees, what type of triangle is it?

Back

It is a right triangle.

Front

What is the relationship between the angles in an isosceles triangle?

Back

In an isosceles triangle, the angles opposite the equal sides are equal.

Front

If a triangle has angles measuring 30 degrees and 60 degrees, what is the measure of the third angle?

Back

The third angle measures 90 degrees (180 - 30 - 60 = 90).

Front

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

Back

You subtract the sum of the known angles from 180 degrees.

Front

What is the sum of the angles in any triangle?

Back

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

Front

If one angle of a triangle is 120 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 60 degrees.