Law of Cosines Calculator

Solve a triangle from two sides and the included angle using the law of cosines, with the third side, area, and remaining angles.

Frequently Asked Questions

When do I use the law of cosines?

Use it when you know two sides of a triangle and the angle between them and need the third side and the remaining angles.

How is it related to the Pythagorean theorem?

When the included angle is 90°, cos(90°) = 0, and the law of cosines c² = a² + b² − 2ab·cos C reduces exactly to a² + b² = c².

Important Disclaimer: Estimates for informational purposes only.

This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.