— FELIX KLEIN v
2 1  Introduction
In Chapter 1, we have studied that the inverse of a function
f, denoted by f –1, exists if f is one-one and onto There are
many functions which are not one-one, onto or both and
hence we can not talk of their inverses In Class XI, we
studied that trigonometric functions are not one-one and
onto over their natural domains and ranges and hence their
inverses do not exist