Law of tangents
![Figure 1 – A triangle. The angles α, β, and γ are respectively opposite the sides a, b, and c.](/Images/godic/202502/15/Triangle_with_notations_2.svg1925.png")
![](/Images/godic/202502/15/Cercle_trigo1925.png")
In trigonometry, the law of tangents is a statement about the relationship between the tangents of two angles of a triangle and the lengths of the opposing sides.
In Figure 1, a, b, and c are the lengths of the three sides of the triangle, and α, β, and γ are the angles opposite those three respective sides. The law of tangents states that