Trigonometry
Law of Cosines (side)
Third side from two sides and included angle.
Formula
Formula
c = √a2 + b2 − 2ab cos C
Variables
| Symbol | Definition | Type & range | Units | Role |
|---|---|---|---|---|
| a, b | two sides | real number (ℝ) | — | input |
| C | included angle (deg) | real number (ℝ) | deg | input |
Try it yourself
Interactive calculator
Worked examples
Example 1
Givena = 5, b = 7, angle C (deg) = 60
Result6.244997998
Example 2
Givena = 8, b = 6, angle C (deg) = 90
Result10