# Triangle Sum Theorem Calculator

Created by Mariamy Chrdileli
Reviewed by Julia Żuławińska
Last updated: Jun 14, 2022

The triangle sum theorem calculator is a convenient tool to help you calculate an unknown angle value in a triangle, given two angles. Are you wondering what the triangle angle sum theorem is? Wonder no more; come along and learn how to use the triangle sum theorem to find the triangle angle you're looking for! 👩‍🏫

## Sum of angles in a triangle - What is the triangle sum theorem

According to the triangle angle sum theorem, the sum of all interior angles in a triangle equals 180°:

α + β + γ = 180°

For instance, if you wanted to determine the unknown angle α in a triangle, you would use the triangle angle sum theorem in the following way:

• α = 180° - γ - β (in degrees)
• α = π - γ - β (in radians)

You can also save time and trust the Omni triangle sum theorem calculator to do your work!

## How do I use the triangle sum theorem calculator?

Using a triangle sum theorem calculator is very straightforward! Just enter two known interior angles of a triangle in the tool. The calculator will tell you the value of a third angle according to the triangle interior angle sum theorem.

You can also change units of measurement for angles as per your convenience!

Do you think the triangle sum theorem calculator is helpful? Come along; we have other related calculators that will make your life easier:

## FAQ

### How do I calculate the third angle in a triangle if two other angles are 40° and 75°?

To calculate the third angle in a triangle if two other angles are 40° and 75°:

1. Add 40 to 75; in other words, sum two known interior angles of a triangle.
2. Take the sum calculated in the previous step, and subtract it from 180.
3. That's all! The value of a third angle is 66°.

### What is the sum of angles in a triangle?

According to the triangle angle sum theorem, the sum of all interior angles in a triangle equals 180°.

Mariamy Chrdileli α
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