Law of Cosines Calculator
Use the law of cosines to find the third side from two sides and the angle between them, or any angle from three sides.
Side c
8.185352772
- Angle A
- 47.78365116°
- Angle B
- 72.21634884°
- Area
- 27.27980022
Show the work
Law of cosines for c to the power of 2
c to the power of 2 = a to the power of 2 + b to the power of 2 − 2ab cos C
7 to the power of 2 + 9 to the power of 2 − 2 × 7 × 9 × cos 60° = 67
Side c is its square root
c = √(c to the power of 2)
√67 = 8.185352772
How it works
c² = a² + b² − 2ab cos C; cos C = (a² + b² − c²) ÷ 2ab
Questions
- How does the law of cosines calculator work?
- c² = a² + b² − 2ab cos C; cos C = (a² + b² − c²) ÷ 2ab.
- What do I need to enter?
- Find, Side a, Side b, Angle C, Side c. Optional fields can be left blank.
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