1. Unit 5 Sum and Difference Identities

2. Finding Exact Value While doing this it is important to remember your 30, 45, and 60 degree angles. Also know each of there values in the different quadrants. The reference angle is always the angle between the terminal side and the x-axis. It will always be 30, 45, or 60.

3. Sum and Difference for cosine Cos (u + v) = (cos u)(cos v) – (sin u)(sin v) Cos (u – v) = (cos u)(cos v) + (sin u)(sin v) Example:Find exact value of cos 15

4. Sum and difference of Sine Sin (u + v) = (sinu)(cos v) + (cos u)(sin v) Sin (u – v) = (sinu)(cos v) – (cos u)(sin v) Example:Find exact value of sin15

5. Sum and difference tangent tan (u + v) = (tan u + tan v)/(1 – (tan u)(tan v)) tan (u – v) = (tan u – tan v)/(1 + (tan u)(tan v)) Find exact value of tan15