Math

Law of Cosines Calculator

Third side from two sides and the included angle (SAS).

Free to use — no sign-up or login.

Side c

This free Law of Cosines Calculator covers Third side from two sides and the included angle (SAS).

c² = a² + b² − 2ab cos C. Related math tools sit beside How it works, with no account required.

Using the Law of Cosines Calculator

Third side from two sides and the included angle (SAS). Typical inputs are Side a, Side b and Included angle C (°). How it works beside the form states the identity the Law of Cosines Calculator applies.

FAQ

How do I use the Law of Cosines Calculator?

Open the Law of Cosines Calculator, fill Side a, Side b and Included angle C (°), and read the result. c² = a² + b² − 2ab cos C.

What formula does the Law of Cosines Calculator use?

The Law of Cosines Calculator uses the identity in How it works. In words: c² = a² + b² − 2ab cos C.