а) 2\sin \dfrac{5\pi}{12} \cos \dfrac{5\pi}{12} = ; б) \left( \cos \dfrac{7\pi}{12} -\sin \dfrac{7\pi}{12}\right) \left( \cos \dfrac{7\pi}{12} + \sin \dfrac{7\pi}{12}\right)= .

Задание

Вычисли

а) \(2\sin \dfrac{5\pi}{12} \cos \dfrac{5\pi}{12} = \) [ ];

б) \(\left( \cos \dfrac{7\pi}{12} -\sin \dfrac{7\pi}{12}\right) \left( \cos \dfrac{7\pi}{12} + \sin \dfrac{7\pi}{12}\right)= \) [ ].