Prove that, `tan^(-1)a+tan^(-1)b+tan^(-1)((1-a-b-ab)/(1+a+b-ab))=(pi)/(4)`.

Prove that, "tan"^(-1)(a)/(b)-"tan"^(-1)((a-b)/(a+b))=(pi)/(4) .

tan ^(-1)"" a+ cot ^(-1)""b=cot ^(-1) ""(b-a)/(1+ab)

Prove that tan4^(@)tan43^(@)tan47^(@)tan86^(@)=1 .

Prove that: tan^(-1)(1/2tan2A)+tan^(-1)(cotA)+tan^(-1)(cot^3A) =0

4 tan ^(-1 )""(1)/(5) - tan ^(-1)""(1)/(239)=(pi)/(4)

prove that , 4 tan ^(-1) ""(1)/(5) -tan ^(-1 )""(1)/(70) + tan ^(-1) ""(1)/(99) = (pi)/(4) .

Prove that, tan^(-1) (4/3) + tan^(-1) (12/5) = pi - tan^(-1)(56/33) .

Prove that , tan^(-1)""x+ tan^(-1) ""y+tan^(-1)""z= tan ^(-1)""(x+y+z-xyz)/(1-xy-yz-zx)

Prove that "tan"^(-1)(ap-q)/(aq+p)+"tan"^(-1)(b-a)/(ab+1)+"tan"^(-1)(c-b)/(bc+1)="tan"^(-1)(p)/(q)-"tan"^(-1)(1)/(c )

prove that tan ^(-1)"" (1)/(4) + tan ^(-1) ""(2)/(9) + tan ^(-1) "" (1)/(5) + tan ^(-1) ""(1)/(8) =(pi)/(4).