Law of Cosines
Calculate Law of Cosines instantly with the exact formula and a worked example. Free online calculator — no signup, works on mobile.
Law of Cosines
a
b
Angle C°
Side c
5.5678
More about: Law of Cosines
What it calculates
The “Law of Cosines” calculator computes Side c from 3 parameters: a, b, angle c (°).
A core calculation for studying, engineering tasks, and checking solutions.
Example calculation
With parameters a = 5, b = 6, Angle C = 60 ° the result is 5.57.
How to use
- Enter the parameter values — every field above is adjustable with a slider.
- The result and related metrics are calculated automatically as you type.
- Use the additional metrics shown (if any) where needed.
- Copy the result or bookmark the page.