This can be visualised by looking the graphs of y = sin x and
y = sin–1 x as given in the same axes (Fig 2 1 (iii)) Like sine function, the cosine function is a function whose domain is the set of all
real numbers and range is the set [–1, 1] If we restrict the domain of cosine function
to [0, π], then it becomes one-one and onto with range [–1, 1]