Let's solve the trig equation >>>
[tex]\begin{gathered} \sqrt[]{2}\cos (3x)-1=0 \\ \sqrt[]{2}\cos (3x)=1 \\ \cos (3x)=\frac{1}{\sqrt[]{2}} \\ 3x=\frac{\pi}{4},\frac{7\pi}{4} \\ x=\frac{\pi}{12},\frac{7\pi}{12} \end{gathered}[/tex]To get the other angles within 2π, we add 2π to these two angles. Thus,
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