Use this triangle law of cosines calculator to calculate triangle sides with law of cosines or find triangle angles law of cosines automatically.
A, B, C = angles in degrees
a, b, c = sides of triangle
| a | b | c | Angle A | Angle B | Angle C |
|---|---|---|---|---|---|
| 3 | 4 | 5 | 36.869898 | 53.130102 | 90.000000 |
| 5 | 5 | 6 | 53.130102 | 53.130102 | 73.739796 |
| 6 | 8 | 10 | 36.869898 | 53.130102 | 90.000000 |
| 7 | 7 | 7 | 60.000000 | 60.000000 | 60.000000 |
| 8 | 15 | 17 | 28.072486 | 61.927514 | 90.000000 |
Use the law of cosines formula manually:
1. A = arccos((b² + c² − a²)/(2bc))
2. B = arccos((a² + c² − b²)/(2ac))
3. C = 180° − A − B
This triangle law of cosines calculator computes all three angles with six-decimal precision automatically as you type. Perfect for students, engineers, and designers.
• Generalizes the Pythagorean theorem.
• Applies to any triangle type.
• Useful in navigation, surveying, and architecture.
• Enables solving oblique triangles.
• Key concept in trigonometry courses.