Simpson's Formulas/Cosine by Sine

Theorem

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

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

Also reported as
This result can also sometimes be seen as:


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