LESSON NOTES MENU
Algebra I / Elem. Algebra
Introduction to Algebra Linear Equations and Inequalities Functions and Graphs I Lines and thier Graphs Linear Systems
Algebra II / E&I Algebra
Exponents & Polynomials Intermediate Algebra starts here!

Factoring Rational Expressions Rational Equations and Applications
Algebra III / Inter. Algebra
Radical Expressions Nonlinear Equations and Applications Functions and Graphs II Exponential and Logarithmic Functions
College Algebra
Equations and Inequalitites Functions and Graphs Polynomial and Rational Functions Exponential and Logarithmic Functions Systems and Matrices Geometry Basics Conic Sections Sequences and Series
Trigonometry
The Six Trigonometric Functions Right Triangle Trigonometry Circular Functions Graphs of Trigonometric Functions Trigonometric Identities Trigonometric Equations Oblique Triangles and the Laws Vectors Complex, Parametric, and Polar Forms
Calculus I
Limits and Continuity Derivatives Analysis of Curves Antiderivatives
Calculus II
Transcendental Functions
Geometry Physics Integration Techniques Calculus of Infinity Parametric, Polar, and Conic Curves
Calculus III
Calculus IV
15.Functions of Several Variables
16.Multiple Integration
17.Vector Analysis

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

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. Supplementary Resources (optional)