The given equation is:
[tex]\sin (3x)=\sqrt[]{3}\cos (3x)[/tex]
Dividing both sides of the equation by cos(3x):
[tex]\frac{\sin(3x)}{\cos(3x)}=\frac{\sqrt[]{3}\cos(3x)}{\cos(3x)}[/tex]
Cancel out the common term in the right hand side of the equation.
[tex]\begin{gathered} \frac{\sin(3x)}{\cos(3x)}=\frac{\sqrt[]{3}\cancel{\textcolor{green}{\cos(3x)}}}{\cancel{\textcolor{green}{\cos(3x)}}} \\ \frac{\sin(3x)}{\cos(3x)}=\sqrt[]{3} \end{gathered}[/tex][tex]\begin{gathered} \text{ Using the trigonometric identity }\frac{\sin(3x)}{\cos(3x)}=\tan (3x),\text{ it follows that} \\ \tan (3x)=\sqrt[]{3} \end{gathered}[/tex]
Therefore,
[tex]3x=\tan ^{-1}(\sqrt[]{3})[/tex]
Hence,
[tex]\begin{gathered} 3x=\frac{\pi}{3}+\pi n\: \\ \text{ Dividing both sides by }3\text{ we have} \\ x=\frac{\pi}{9}+\frac{\pi n}{3} \end{gathered}[/tex]
x = π / 9 + (πn)/3
.