Math
Law of cosines.
Definition
A formula that relates the lengths of the sides of any triangle to the cosine of one of its angles. It generalizes the Pythagorean theorem to non-right triangles and is used when you know two sides and the included angle (SAS) or all three sides (SSS).
Examples
Real-world.
- 1 Finding the third side of a triangle when two sides are 7 and 10 with an included angle of 60°
- 2 Determining an angle when all three side lengths are known
- 3 Calculating the distance between two ships given their distances from a lighthouse and the angle between them
Key Fact
c² = a² + b² − 2ab·cos(C)