It means that sec (secant function) assumes
all real values except –1 < y < 1 and is not defined for odd multiples of 2
π If we
restrict the domain of  secant function to [0, π] – { 2
π }, then it is one-one and onto with
Fig 2 3 (i)
Fig 2 3 (ii)
Rationalised 2023-24
INVERSE TRIGONOMETRIC FUNCTIONS     23
its range as the set R – (–1, 1)