№6. Доказать тождество [m]\frac{2\cos\left(\frac{\pi}{6} - 2\alpha\right) - \sqrt{3}\sin\left(2,5\pi - 2\alpha\right)}{\cos\left(4,5\pi - 2\alpha\right) + 2\cos\left(\frac{\pi}{6} + 2\alpha\right)} = \frac{tg{2\alpha}}{\sqrt{3}}[/m].