Use identities to find value of 

Solve the equation for exact solutions

Use a sum or difference formula to find the exact value of the trigonometric function

Find the solutions to the equation in the interval 

Simplify the algebraic expression and the corresponding trigonometric expression.

Write the given expression as a function of x.

Find all solutions of this equation:

Complete the identity

Find the other trigonometric functions of 

Use an identity to evaluate the expression