– bul formulalar tómendegishe boladı: $$\begin{array}{lll} 1. & \sin\alpha\cos\alpha=\dfrac{\sin(\alpha-\beta)+\sin(\alpha+\beta)}{2},\\ 2. & \sin\alpha\sin\beta=\dfrac{\cos(\alpha-\beta)-\cos(\alpha+\beta)}{2}, \\3. & \cos\alpha\cos\beta=\dfrac{\cos(\alpha-\beta)+\cos(\alpha+\beta)}{2}.\end{array}$$