Trigonometry For Dummies, 2nd Edition

Chapter 15

Investigating Inverse Trig Functions

In This Chapter

Acquainting yourself with inverse notation

Setting limits on inverse trig functions

Determining domain and range of inverse trig functions

As thrilling and fulfilling as the original six trig functions are, they just aren't complete without their inverses. An inverse trig function behaves like the inverse of any other type of function — it undoes what the original function did. In mathematics, functions can have inverses if they're one-to-one, meaning each output value occurs only once. This whole inverse idea is going to take some fast talking when it comes to trig functions, because they keep repeating values over and over as angles are formed with every full rotation of the circle — so you're going to wonder how these functions and inverses can be one-to-one. If you need a refresher on basic inverse functions, flip on back to Chapter 3 for the lowdown on them and how you determine one.

Writing It Right

You use inverse trig functions to solve equations such as

or sec x = –2, or tan 2x = 1. In typical algebra equations, ...