Half Angle Formula of `tan(A/2), tan (B/2), tan (C/2)`

* In a Delta ABC,If tan((A)/(2)),tan((B)/(2)),tan((C)/(2)) are in H.P.then a,b,c are in ,tan((C)/(2))

(tan(B/2)-tan(C/2))/(tan(B/2)+tan(C/2))

s^(2)tan((A)/(2))tan((B)/(2))tan((C)/(2))

If A+B+C=pi , prove that : tan( A/2) tan (B/2) + tan (B/2 )tan (C/2)+ tan( C/2) tan (A/2) =1

In DeltaABC , Prove that (s-a) tan (A/2)=(s-b) tan (B/2)=(s-c) tan (C/2)

If A,B,C are angles of a triangle ,then the minimum value of tan^(2)(A/2)+tan^(2)(B/2)+tan^(2)(C/2) , is

In /_ABC with usual notations,if a,b,c are in A.P.then the numerical value of tan((A)/(2))tan((B)/(2))+tan((B)/(2))tan((C)/(2)) is