CK-12 Foundation
Ck 12: Trigonometry: Trigonometric Equations Using Factoring
[Free Registration/Login may be required to access all resource tools.] This lesson covers solving trigonometric equations using factoring, square roots, and the quadratic formula.
CK-12 Foundation
Ck 12: Trigonometric Equations Using Half Angle Formulas
[Free Registration/Login may be required to access all resource tools.] Here you'll learn how to solve trigonometric equations using the half angle formulas.
Purple Math
Purplemath: Solving Simple (To Medium Hard) Trig Equations
Introduces techniques for solving trigonometric equations. Provides worked examples of solving some simpler to medium-hard equations.