Corresponding to each of these intervals, we get different branches of the function sec–1 The branch with range [0, π] – { 2
π } is called the principal value branch of the
function sec–1 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)