Free · Algebra and geometric relations

Triangle Angles from Side or Angle Data

Use SSS, included-angle SAS or two known angles to find triangle interior angles.

Calculator inputs

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Enter the known values in the units shown. Results update as you type.
Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
Use the worked example to check the method. Reset restores the starting fields.

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

For the worked example, γ = 90.

cos α=(b²+c²−a²)/(2bc); α+β+γ=180°

Enter these known values and leave the other values blank.

SSS lengths obey strict triangle inequalities and angles are strictly between zero and 180 degrees.
SAS needs an included angle. Angles face the correspondingly named sides.

Choose the relevant mode and enter independent known quantities. Leave a missing value empty where the control permits an inverse.

The result follows the stated mathematical model. All dimensions must use consistent units; available unit selectors handle conversions.

Bookify validates the real geometric or algebraic domain and inverse branches omitted or approximated by this capture.