PENJUMLAHAN DAN PERKALIAN
\(\sin A + \sin B = 2 \sin \frac{1}{2} (A + B) \cos \frac{1}{2} (A - B)\)
\(\sin A - \sin B = 2 \cos \frac{1}{2} (A + B) \sin \frac{1}{2} (A - B)\)
\(\cos A + \cos B = 2 \cos \frac{1}{2} (A + B) \cos \frac{1}{2} (A - B)\)
\(\cos A - \cos B = -2 \sin \frac{1}{2} (A + B) \sin \frac{1}{2} (A - B)\)
\(2 \sin A \cos B = \sin (A + B) + \sin (A - B) \)
\(2 \cos A \sin B = \sin (A + B) - \sin (A - B) \)
\(2 \cos A \cos B = \cos (A + B) + \cos (A - B) \)
\(-2 \sin A \sin B = \cos (A + B) - \cos (A - B) \)