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.

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