tan−1x+y+z+xyz1+xy+yz+zx\tan ^{-1} \frac{x+y+z+x y z}{1+x y+y z+z x}tan−11+xy+yz+zxx+y+z+xyz
tan−1x+y+z−xyz1−xy−yz−zx\tan ^{-1} \frac{x+y+z-x y z}{1-x y-y z-z x}tan−11−xy−yz−zxx+y+z−xyz
tan−1x+y+z+xyz1−xy−yz−zx\tan ^{-1} \frac{x+y+z+x y z}{1-x y-y z-z x}tan−11−xy−yz−zxx+y+z+xyz
tan−1x+y+z−xyz1+xy+yz+zx\tan ^{-1} \frac{x+y+z-x y z}{1+x y+y z+z x}tan−11+xy+yz+zxx+y+z−xyz
