Prove that `tan(A+B+C)=(tanA+tanB+tanC-tanAtanBtanC)/(1-tanAtanB-tanBtanC-tanCtanA)`

In DeltaABC , tanA+tanB+tanC=tanAtanBtanC

tanA +tanB + tanC = tanA tanB tanC if

If tanA+tanB+tanC=tanA.tanB.tanC , then-

Prove that: (tanA + tanB)/(cotA+cotB)=tanAtanB

Prove that- sin(A-B)/sin(A+B)= (tanA-tanB)/(tanA+tanB)

Prove that- sin(A-B)/sin(A+B)= (tanA-tanB)/(tanA+tanB)

If A+B+C=180^(@) , then (tanA+tanB+tanC)/(tanAtanBtanC)=?

If A, B, C, D be the angles of a quadrilateral, prove that : (tanA+tanB+tanC+tanD)/(cotA+cotB+cotC+cotD) = tan A tan B tan C tan D

If A+C=B,then tanA tanBtanC=