In a triangle, the name given to this relation:

[latex]\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}}[/latex]

where A and B are the measures of the angles opposite the sides of measures [latex]a[/latex] and [latex]b[/latex] of any triangle.