Cos^2 x -0,5sin 2x =1

[latex]cos^2x-0.5sin 2x=1 \ cos^2x-0.5cdot 2sin xcos x=cos^2x+sin^2x \ -sin xcos x-sin^2x=0 \ -sin x(cos x+sin x)=0 \ left[egin{array}{ccc}sin x=0\ tg x=-1end{array}ighto left[egin{array}{ccc}x_1= pi k,k in Z\ x_2=- frac{pi}{4} + pi n,n in Zend{array}ight[/latex]