We thus have
sec–1 : R – (–1,1) → [0, π] – { 2
π }
The graphs of the functions y = sec x and y = sec-1 x are given in Fig 2 4 (i), (ii) Finally, we now discuss tan–1 and cot–1
We know that the domain of the tan function (tangent function) is the set
{x : x ∈ R and x ≠ (2n +1) 2
π , n ∈ Z} and the range is R It means that tan function
is not defined for odd multiples of  2
π