Sin^4(x/2)-cos^4(x/2)=1/2

[latex]\sin^4 \frac{x}{2} -\cos^4\frac{x}{2}=0.5\\\\ (\sin^2\frac{x}{2}+\cos^2\frac{x}{2})(\sin^2\frac{x}{2}-\cos^2\frac{x}{2})=0.5\\ \\ \cos^2\frac{x}{2}-\sin^2\frac{x}{2}=-0.5\\ \\ \cos x=-0.5\\ \\ x=\pm \frac{2\pi}{3} +2\pi n,n \in Z[/latex]