Cos^2x-sin^2x=sqrt 2/2

[latex]cos^2x-sin^2x= \frac{ \sqrt{2} }{2} [/latex] [latex]cos2x= \frac{ \sqrt{2} }{2} [/latex] [latex]2x=бarccos \frac{ \sqrt{2} }{2} +2 \pi n,[/latex] [latex]n[/latex] ∈ [latex]Z[/latex] [latex]2x=б\frac{ \pi }{4} +2 \pi n,[/latex] [latex]n[/latex] ∈ [latex]Z[/latex] [latex]x=б\frac{ \pi }{8} + \pi n,[/latex] [latex]n[/latex] ∈ [latex]Z[/latex]