Question

как это решить?
how to solve this?

Answer 1

$\displaystyle \frac{cosa}{sina} -\frac{sina}{cosa} -\frac{2sin2a}{cos2a} =\\\\ =\frac{cos^2a-sin^2a}{sinacosa} -\frac{2sin2a}{cos2a} =\\\\ =\frac{2cos2a}{sin2a} -\frac{2sin2a}{cos2a} =\\\\ =\frac{2cos^22a-2sin^22a}{sin2acos2a} =\\\\ =\frac{4cos4a}{sin4a} =\frac{4}{tg4a} =\\\\=\frac{4}{-\frac{2}{5}} =-\frac{4*5}{2}=-10$