(2sin^2x-sin2x-2cos2x)/sqrt(1-x^2)=0

(2 * sin^2 x - sin (2 * x) - 2 * cos (2 * x))/(1 - x^2) = 0; 

Уравнение не имеет корней, если х = 1 и х = -1. 

2 * sin^2 x - sin (2 * x) - 2 * cos (2 * x) = 0;  

2 * sin^2 x - sin (2 * x) - 2 * (cos^2 x - sin^2 x) = 0; 

2 * sin^2 x - sin (2 * x) - 2 * cos^2 x + 2 * sin^2 x = 0; 

4 * sin^2 x - 2 * sin x * cos x - 2 * cos^2 x  = 0; 

4 * tg x - 2 * tg x - 2 = 0; 

2 * tg x - tg x - 1 = 0;  

D = 1^2 - 4 * 2 * (-1) = 1 + 8 = 9; 

1) tg x = -1/2;  

x = arctg (-1/2) + pi * n;  

x = -arctg (1/2) + pi * n;  

2) tg x = -1;  

x = arctg (-1) + pi * n; 

x = -pi4 + pi * n.