1. Verifying Trig Identities Today you will be verifying trigonometric identities to prove that a trigonometric equation is true for any replacement of the variable within the domain.

2. Procedure for Verifying Trigonometric Identities Draw a vertical line below the equal sign of the equation. Determine which side of the identity to change (usually the more complicated side). Use fundamental identities and algebraic properties to change the chosen side into the other side.

3. Strategies for Verifying: Combining Fractions (common denominators) Separating Fractions Multiplying the numerator and denominator by the same expression. Reducing Fractions Simplifying complex rational expressions Combining Like Terms Factoring Expanding Powers Changing all trigonometric expressions to sines and cosines

4. Caution Verifying an identity is not the same as solving an equation. Therefore, such equation-solving techniques such as operating on both sides are not to be used in the proof of an identity.

5. Examples

11. Assignment A 3.13 Sect III A & B pg. 460-61 #11-27 (odd)