Преобразовать в произведение 1-2sina

[latex]1-2sin alpha =2cdot frac{1}{2}-2sin alpha =2cdot sinfrac{pi}{6}-2sin alpha =\\=2cdot (sinfrac{pi}{6}-sin alpha )=2cdot 2sinfrac{frac{pi}{6}- alpha }{2}cdot cosfrac{frac{pi}{6}+ alpha }{2}=\\=4cdot sin(frac{pi}{12}-frac{ alpha }{2})cdot cos(frac{pi}{12}+ frac{ alpha }{2})[/latex]