Pre-Calculus For Dummies, 2nd Edition

Chapter 8

Identifying with Trig Identities: The Basics

In This Chapter

Reviewing the basics of solving trig equations

Simplifying and proving expressions with fundamental trig identities

Handling more complicated proofs

In this chapter and the next, you work on simplifying expressions using basic trig identities to prove more complicated identities and solving equations that involve trig functions. Because we’re fans of building momentum, we’re going to start off slow with the basics. This chapter covers basic identities, which are statements that are always true and that you use throughout an entire equation to help you simplify the problem, one expression at a time, prior to solving it. And you’re in luck, because trig has many of these identities.

The hard thing about simplifying trig expressions by using trig identities, though, is knowing when to stop. Enter proofs, which give you an end goal so that you know when you’ve hit a stopping point. You use proofs when you need to show that two expressions are equal even though they look completely different. (If you thought you were done with proofs when you moved past geometry, think again!)

If you listen to one piece of advice, ...