Question

Даю 25 баллов, 13.12 задание. Срочно!​

Answer 1

$\displaystyle\frac{2tg75`}{1-tg^275`}=tg 2*75`=tg 150`=tg(90`+60`)= -ctg60`=-\frac{1}{\sqrt{3}}\\\\2sin\frac{3\pi }{8}*cos\frac{3\pi }{8}=sin2*\frac{3\pi }{8}=sin\frac{3\pi }{4}=\frac{\sqrt{2}}{2}\\\\1-2cos^2\frac{\pi}{12}=-cos2*\frac{\pi }{12}=-cos\frac{\pi }{6}=-\frac{\sqrt{3}}{2}$