Sum and Difference Trigonometric Identities are the relationships between two angles using sine, cosine, and tangent. There are sum(+) formulas for sin, cos, and tan, as well as the difference(-) formulas for sin, cos, tan. Usually they are written as one formula by putting the addition sign on top of the minus sign and vice versa, however i have broken it up to make it more comprehensible.
Difference Formulas: 1. sin(a - b) = sin(a)cos(b)-cos(a)sin(b) 2. cos(a - b) = cos(a)cos(b) + sin(a)sin(b) 3. tan(a - b) = tan(a) - tan(b) / 1 + tan(a)tan(b)
**Note: in the video below "a" is represented as "alpha" and "b" is represented as "beta" but it doesn't matter and they are the same thing just shown in a different form!**