Why do triangle angles add up to 180 degrees?

This is a fundamental property of Euclidean geometry. It can be proven by drawing a line parallel to one side through the opposite vertex and using alternate interior angles.

Can a triangle have two right angles?

No. Two right angles would sum to 180°, leaving 0° for the third angle, which is impossible. A triangle can have at most one right angle or one obtuse angle.

Free Triangle Angle Calculator

Find the missing angle of a triangle when you know the other two angles. The sum of all angles in a triangle is always 180 degrees.

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Angle A

degrees

Angle B

degrees

Angle C

50.00 degrees

Sum Check180 degrees

Triangle Type0

View formula & how it works →

How to Find a Missing Triangle Angle

Formula

Angle C = 180° - Angle A - Angle B

The sum of all interior angles of a triangle is always 180 degrees. If you know two angles, you can find the third by subtracting their sum from 180.

Triangle Types by Angles

Acute: All angles less than 90°

Right: One angle exactly 90°

Obtuse: One angle greater than 90°

Example Calculation

A triangle has angles of 60° and 70°. Find the third angle.

01Angle C = 180° - 60° - 70°
02= 180° - 130°
03= 50°

Frequently Asked Questions

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