Prosthaphaeresis Formulas/Sine minus Sine

Theorem

 * $\sin \alpha - \sin \beta = 2 \map \cos {\dfrac {\alpha + \beta} 2} \map \sin {\dfrac {\alpha - \beta} 2}$

where $\sin$ denotes sine and $\cos$ denotes cosine.

Also see

 * Sine plus Sine
 * Cosine plus Cosine
 * Cosine minus Cosine