We can, therefore, define the inverse of cosine function in each of these
intervals We denote the inverse of the cosine function by cos–1 (arc cosine function) Thus, cos–1 is a function whose domain is [–1, 1] and range
could be any of the intervals [–π, 0], [0, π], [π, 2π] etc Corresponding to each such interval, we get a branch of the
function cos–1