Solution:
Consider the following trigonometric equation:
[tex]3\cot (\theta)=-\sqrt[]{3}[/tex]This is equivalent to:
[tex]\cot (\theta)=-\frac{\sqrt[]{3}}{3}[/tex]now, consider the following trigonometric circle and the above equation:
According to this trigonometric circle and the definition of the cotangent function, we can conclude that the general solution would be:
[tex]\theta=\frac{2\pi}{3}+\pi n[/tex]