Module 5-II – Trigonometric Functions

Section 5-II.3 – Trigonometric Identities

Introduction

After working hard to solve an algebra problem you check the answer and it looks different from yours. But after a moment of panic, you realize that it’s really just saying the same thing in a different way. This can often be seen by means of an algebraic identity (i.e. an equation, like x^2+2x+1=(x+1)^2, which is true for all values of the variable). You also frequently use identities to simplify expressions and to rearrange the terms in an equation to make it easier to find a solution. 

Identities involving trigonometric functions are important for similar reasons. You have already seen some examples, and in this section you will find more, and will also learn how to work with identities you know in order to get new ones.
 

What to Do

1.         Read section 6.1 of the text.

2.         Read the following Study Notes and Discussion (and whatever text sections they refer you to), and make sure that you have absorbed the main points by answering the questions.

3.         Read sections 6.3, and 6.4 of the text. 

4.         Follow the instructions regarding Practice. When you have met the Learning Objectives for this Section, go on to the next.


Go To:    Sec 5-II.0    Sec 5-II.1    Sec 5-II.2    Sec 5-II.3    Sec 5-II.4