0≤tan−1(x)<π20 \leq \tan ^{-1}(x)<\frac{\pi}{2}0≤tan−1(x)<2π
−π2<tan−1(x)<0-\frac{\pi}{2}<\tan ^{-1}(x)<0−2π<tan−1(x)<0
0<tan−1(x)<π20<\tan ^{-1}(x)<\frac{\pi}{2}0<tan−1(x)<2π
−π2≤tan−1(x)<0-\frac{\pi}{2} \leq \tan ^{-1}(x)<0−2π≤tan−1(x)<0
