Triangle Sum Theorem

Front

What is the Triangle Sum Theorem?

Back

The Triangle 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 can you say about the other two angles?

Back

The other two angles must sum to 90 degrees, making the triangle a right triangle.

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

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

Front

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

Back

The third angle measures 90 degrees.

Front

What is the relationship between the angles in a triangle and the exterior angle?

Back

The exterior angle of a triangle is equal to the sum of the two opposite interior angles.

Front

If one angle of a triangle is 70 degrees and another is 50 degrees, what is the third angle?

Back

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

Front

What is the formula to calculate the sum of angles in a triangle?

Back

The formula is: Angle1 + Angle2 + Angle3 = 180 degrees.

Front

In a triangle, if one angle is twice the size of another, how can you express this relationship?

Back

Let the smaller angle be x; then the larger angle is 2x. The equation is x + 2x + third angle = 180.

Front

What type of triangle has all angles less than 90 degrees?

Back

An acute triangle.