(1-сos2x)²/4+(1+сos2x)²/4=sin2x-0,5
(1-2cos2x+cos²2x+1+2cos2x+cos²2x)=4sin2x-2
2+2cos²2x-4sin2x+2=0
cos²2x-2sin2x+2=0
1-sin²2x-2sin2x+2=0
sin²2x+2sin2x-3=0
sin2x=a
a²+2a-3=0⇒a1+a2=-2 U a1*a2=-3
a1=-3⇒sin2x=-3∉[-1;1]-нет решения
a2=1⇒sin2x=1⇒2x=π/2+2πn⇒x=π/4+ππn