Precalculus - Trigonometric Identities and Equations (Transformation)

Solve trigonometric equations by using transformation method.
Sum-difference identities:
sin⁡(A±B) = sin⁡Acos⁡B ± cos⁡Asin⁡B
cos⁡(A±B) = cos⁡Acos⁡B ∓ sin⁡Asin⁡B