This section will teach you how to solve a trigonometric equation when the functions have multiple angles.
Textbook Page- 387
Chapter-5.5
Example- 2cosx + sin2x =0
First Begin by rewriting the equation so it involves only x rather than 2x

2cosx+sin2x=0

double angle formula

2cosx(1+sinx)=0

factor

cosx=0 sinx+1=0

set factors equal to zero

x=pi/2, 3pi/2 , x=3pi/2

Solve

Tips, Tricks, and Advice
1. Identify the number of trigonometric function in the equation
2. Identify thee arguments of the trigonometric functions
a. how many arguments are there?
b. are the arguments the same or different?
3. Consider making a substitution using the know trigonometric identities.
a. Consider using an expanded form of an expression
b. Consider using a condensed form of an expression and working with multiple rotations.

Textbook Page- 387

Chapter-5.5

Example- 2cosx + sin2x =0

First Begin by rewriting the equation so it involves only x rather than 2x

Tips, Tricks, and Advice

1. Identify the number of trigonometric function in the equation

2. Identify thee arguments of the trigonometric functions

a. how many arguments are there?

b. are the arguments the same or different?

3. Consider making a substitution using the know trigonometric identities.

a. Consider using an expanded form of an expression

b. Consider using a condensed form of an expression and working with multiple rotations.

Pratice Problems

Derive

1. sin3x

Solve

2. cos2x=2sinx

3. cos2x=2sin^2x-cos^2x

4. 3sinx= 2sinx

Websites

http://oakroadsystems.com/math/trigsol.htm

http://www.clickandclimb.com/content/mathcontent/trigonometry/solving_trigonometric_equations.php