Trigonometry For Dummies, 2nd Edition

Chapter 14

Sleuthing Out Identity Solutions

In This Chapter

Handling fractions with care

Maneuvering with handy algebraic tricks

Getting creative with math operations to prove identities

Proving a trig identity can be a simple chore, or it can be a challenge. The nice thing about an identity is that you know that it can be proved — it's an identity, for goodness sake. Some identities seem to just call out with the methods needed to prove them. “Look at me! Look at the three terms on the right that begging to be combined!” Other identities just sit there — daring you to do anything about them.

In this chapter, you find more techniques and suggestions for handling identities. You always want to find the simplest way, first . . . if there is a simplest way. If the easy road fails you, then get on this super highway of trigonometric maneuvers.

Fracturing Fractions

The ratio and reciprocal identities involve fractions. The half-angle identities use fractions. You just can't get away from them. Actually, an identity with fractions can work to your advantage. You can work toward getting rid of the fraction and, in the process, solve the problem. Some of the main techniques for working ...