Free · Algebra and geometric relations

Triangle Angles and Side Classification

Calculate interior angles and identify right, acute or obtuse and equal-side categories.

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.

SSS uses the cosine law; SAS uses c²=a²+b²−2ab cos γ

Enter these known values and leave the other values blank.

A strict triangle has positive sides satisfying all three triangle inequalities.
Classification compares the calculated angles and sides exactly; nearly equal measurements may classify differently after display rounding.

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.