Question

СРОЧНО! ПОМОГИТЕ ПОЖАЙЛУСТА РЕШИТЬ(

Answer 1

Ответ:

Объяснение:

$\frac{2tg(75)}{1-tg^275} = \frac{\frac{2sin75}{cos75}}{1 - \frac{sin^275}{cos^275} } = \frac{2sin75}{cos75} * \frac{cos^275}{cos^275-sin^275} = \frac{2sin75cos75}{cos(2*75)} = \frac{sin150}{cos150} = tg150 = -tg30 = -\frac{\sqrt{3}}{3}$

$2sin\frac{3\pi}{8} cos\frac{3\pi}{8} = sin\frac{3\pi}{4} = \frac{\sqrt{2}}{2}$

$1 - 2cos^2\frac{\pi}{12} = sin^2\frac{\pi}{12} + cos^2\frac{\pi}{12} -2cos^2\frac{\pi}{12} = \\sin^2\frac{\pi}{12}-cos^2\frac{\pi}{12} = -cos\frac{\pi}{6} = -\frac{\sqrt{3}}{2}$