Question

Решить уравнение!!sin^2 x(pi-a) cos^2(pi + a) - 1/4sin^2(2a+3pi)

Answer 1

$sin^2(\pi -a)cos^2(\pi +a)-\frac{1}{4}sin^2(2a+3\pi )=sin^2acos^2a-\frac{1}{4}sin^22a=\\\\=(sina\cdot cosa)^2-\frac{1}{4}sin^22a=(\frac{1}{2}sin2a)^2-\frac{1}{4}sin^22a=\\\\=\frac{1}{4}sin^22a-\frac{1}{4}sin^22a=0$