Trig Sum & Difference Identities
For angles α and β, the following sum and difference identities may be applied:
(1) sin(α + β) = sin α cos β + sin β cos α
(2) sin(α − β) = sin α cos β − sin β cos α
(3) cos(α + β) = cos α cos β − sin α sin β
(4) cos(α − β) = cos α cos β + sin α sin β
Other Trigonometric Identities:
- Reciprocal Identities
- Pythagorean Identities
- Even-Odd Identitites
- Cofunction Identities
- Half-Angle Identities
- Double-Angle Identities
- Sum and Difference Identities
- Sum to Product Identities
- Product to Sum Identities