law of cosines

Noun

 * 1)  A generalization of the Pythagorean theorem that relates the lengths of the sides of a triangle to the cosine of one of its angles.

Usage notes
Let $a, b$, and $c$ be the lengths of the sides of a triangle opposite angles $A, B$, and $C$. The law of cosines states
 * $$a^2 = b^2 + c^2 - 2bc\cos{A}$$
 * $$b^2 = a^2 + c^2 - 2ac\cos{B}$$
 * $$c^2 = a^2 + b^2 - 2ab\cos{C}$$.

Translations

 * Danish: cosinusrelationen
 * Finnish: kosinilause
 * German: Kosinussatz
 * Hungarian:
 * Italian: teorema del coseno
 * Romanian: teorema cosinusului
 * Tagalog: kasinwaying batas