Sometimes we have to factor expressions, expand expressions, find common denominators, or use other algebraic strategies to obtain the desired result. To verify the trigonometric identities, we usually start with the more complicated side of the equation and essentially rewrite the expression until it has been transformed into the same expression as the other side of the equation. Consequently, any trigonometric identity can be written in many ways. We already know that all of the trigonometric functions are related because they all are defined in terms of the unit circle. Basic properties and formulas of algebra, such as the difference of squares formula and the perfect squares formula, will simplify the work involved with trigonometric expressions and equations. In fact, we use algebraic techniques constantly to simplify trigonometric expressions. They are the basic tools of trigonometry used in solving trigonometric equations, just as factoring, finding common denominators, and using special formulas are the basic tools of solving algebraic equations. Identities enable us to simplify complicated expressions. Verify the fundamental trigonometric identities Simplify trigonometric expressions using algebra and the identities.Verify the fundamental trigonometric identities.

Sin starting with 5