The correct option is
A π4x+xcot−1x−12log(1+x2)+ccosecθ=√1+x2
sinθ=1√1+x2
∫cot−1(x−1x+1)dx
x=cotθ
∫cot−1(cotθ−1cotθ+1)[cosec2θ]dθ
−∫cot−1[cot(π/4+θ)](cosec2θ)dθ
=−∫(π/4+θ(cosec2θ))dθ
=−[∫π/4cosecγθdθ+∫θcosecγθdθ]
=−[−π/4cotθ+[θ(−cotθ)+∫cotθdθ]
=π/4cotθ+cotθ−log|sinθ|+c
=π/4x+xcot−1x−1/2log(√1+x2)+c
∫cot−1(x−1x+1)dx=π/4x+xcot−1x−1/2log(√1+x2)+c