Tangent-half-angle in a triangle for JEE

Formula

\(\tan\dfrac{A}{2}=\sqrt{\dfrac{(s-b)(s-c)}{s(s-a)}}\)

Variables: \(a,b,c\) are sides opposite angles \(A,B,C\); \(s=\dfrac{a+b+c}{2}\).

Conditions: For a triangle.

Triangle geometry and half-angle evaluation.