
Vincent L. answered 11/30/22
Mechanical Engineering Undergrad
Trig. functions have a domain defined everywhere (-Ꝏ,Ꝏ), except for Tan, which is undefined when cos is 0, and Cot, which is undefined when sin is 0. However, they are not 1-1 functions. A 1-1 function is a function that passes the horizontal line test: Only one y-value can correspond to one x value.
Trig functions are made 1-1 by restricting the domains. Once made 1-1, simply swap the domain and range to get the inverse trig functions.