Here are the general steps in proving trigonometric identities:

  1. Start with one side. If you get stuck, then continue on other side.
  2. Rewrite all secants, cosecants, tangents, and cotangents in terms of sines and cosines.
  3. Use other known trig identities to simplify more complicated expressions. Avoid taking square roots or raising to powers. Do not cross multiply.
  4. Find a common denominator.
  5. Simplify whenever you can by combining like terms and factoring.

As you work, you should note any restrictions on the variable.