Fórmulas de suma y diferencia de funciones trigonométricas:
\begin{align} \sin (\alpha \pm \beta) &= \sin \alpha \cos \beta \pm \sin \beta \cos \alpha \\ \\ \cos (\alpha \pm \beta) &= \cos \alpha \cos \beta \mp \sin \alpha \sin \beta \\ \\ \tan (\alpha \pm \beta) &= \frac{\tan \alpha \pm \tan \beta}{1 \mp \tan \alpha \tan \beta} \\ \\ \cot (\alpha \pm \beta) &= \frac{\cot \alpha \cot \beta \mp 1}{\cot \beta \pm \cot \alpha} \\ \end{align}