Solve for a missing side or angle in any triangle using the Law of Cosines.
Solve For
Result
Side c4.9500 units
About this calculator
Law of Cosines
The Law of Cosines relates the lengths of the sides of a triangle to the cosine of one of its angles. It generalizes the Pythagorean theorem to non-right triangles.
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Pro Tips
Use this rule when you know SAS (Side-Angle-Side) to find the opposite side.
Use this rule when you know SSS (Side-Side-Side) to find an angle.
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Fun Facts
"If the angle C is 90°, cos(90°) is 0, and the formula becomes a² + b² = c² (Pythagoras)."
