8-9-tan^(-1)((pi)/(9))-tan^(-1)((x-y)/(x+y))dy" equal to "

Prove that tan^(-1)((x)/(y))-tan^(-1)((x-y)/(x+y)) is (pi)/(4) and Not(-3 pi)/(4)

tan^(-1)x+tan^(-1)y=pi+tan^(-1)((x+y)/(1-xy))

If tan^(-1)x+tan^(-1)y=(pi)/(4), then (1+x)(1+y) is equal to

If y=tan^(-1)(cot((pi)/(2)-x)) then (dy)/(dx) is equal to

tan^(-1)(tan""(9pi)/(8)) ………

tan^(-1)x+tan^(-1)y is equal to

The solution of (dy)/(dx)=((x-1)^2+(y-2)^2tan^(- 1)((y-2)/(x-1)))/((x y-2x-y+2)tan^(- 1)((y-2)/(x-1))) is equal to

The solution of (dy)/(dx)=((x-1)^2+(y-2)^2tan^(- 1)((y-2)/(x-1)))/((x y-2x-y+2)tan^(- 1)((y-2)/(x-1))) is equal to

The solution of (dy)/(dx)=((x-1)^2+(y-2)^2tan^(- 1)((y-2)/(x-1)))/((x y-2x-y+2)tan^(- 1)((y-2)/(x-1))) is equal to

The solution of (dy)/(dx)=((x-1)^(2)+(y-2)^(2)tan^(-1)((y-2)/(x-1)))/((xy-2x-y+2)tan^(-1)((y-2)/(x-1))) is equal to