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Calculus III

Course: Trigonometry
Topic: Trigonometric Identities
Subtopic: Double-Angle Identities

Overview

Continuing to expand our arsenal of useful trigonometric formulae, in today's lesson we study the double-angle identities which expand trig functions of a double-angle such as cos(2x). These are some of the most useful identities of all.

Objectives

By the end of this topic you should know and be prepared to be tested on:

• 5.3.1 Use double-angle formulae to evaluate trig functions
• 5.3.2 Use double-angle formulae to prove other trig identities
• 5.3.3 Solve problems involving a double-angle

Terminology

Terms you should be able to define: double-angle

You do not need to memorize these DOUBLE ANGLE IDENTITIES.
You do need to know how to apply them. Keep a copy handy.

Mini-Lectures and Examples

Supplementary Resources (optional)

rev. 2020-10-19