#1/x=1/tan^(-1)t#
Note that #1/x=x^(-1)# does not mean that #1/x=tant#
as #x=tan^(-1)t# means the angle #x#, whose tangent is #t# and this does not mean that tangent of angle #1/x# is #1/t# or #1/tant# or any other thing apparently similar.
In short, #tan^(-1)t# is different from #1/tant#. The fact is that the latter is #cott#, a ratio, while #x# is an angle, which could be in degrees, radians or even Grads.