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Triangle Third Angle Calculator

Find the third interior angle of a triangle from the other two angles.

Angle C (degrees): -
Visual representation

Triangle Third Angle Calculator diagram

The diagram updates with your entries and is illustrative, not necessarily drawn to scale.

Calculation explained

How this result was calculated

The formula, your substituted values, and the evaluated result are shown below.

Both angles must be positive and their sum must be less than 180°. Interior triangle angles total 180°.
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How the Triangle Third Angle Calculator works

Find the third interior angle of a triangle from the other two angles.

Formula

180-angleA-angleB

How to use this calculator

  1. Enter every measurement using one consistent length or angle unit.
  2. Select Calculate to evaluate the formula.
  3. Review the substituted values in the calculation explanation.

Interpretation and limitations

Both angles must be positive and their sum must be less than 180°. Interior triangle angles total 180°. Decimal answers are rounded for display; retain additional precision for subsequent calculations.

Geometry collection

This calculator belongs to the Plane Geometry section of the Math calculator library.

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