# Tangent Law

## Tangent Law

In a triangle, the name given to this relation:

$$\dfrac{\textrm{tan}\dfrac{\textrm{A}+\textrm{B}}{2}}{\textrm{tan}\dfrac{\textrm{A}-\textrm{B}}{2}} = \dfrac{\dfrac{a + b}{2}}{\dfrac{a\space–\space b}{2}}$$

where A and B are the measures of the angles opposite the sides of measures $$a$$ and $$b$$ of any triangle.