Triangle Solver

Solve triangle sides and angles using common formulas.

Enter the three sides of a triangle to calculate its properties.

How to Do It Manually

Given enough information about a triangle's sides and angles, you can solve for the rest using the Law of Sines and Law of Cosines.

Law of Sines: a/sin(A) = b/sin(B) = c/sin(C) | Law of Cosines: c² = a² + b² − 2ab·cos(C)
  1. If you have all three sides (SSS): use the Law of Cosines to find each angle.
  2. If you have two sides and included angle (SAS): use the Law of Cosines to find the third side.
  3. If you have two angles and a side (AAS/ASA): use the Law of Sines.
  4. Right triangles: use the Pythagorean Theorem (a² + b² = c²).

Frequently Asked Questions

What is the sum of angles in a triangle?

All interior angles of any triangle always add up to 180°.