[tex]9+\cot^2x=12[/tex]
[tex]\cot^2x=3[/tex]
[tex]\cot x=\pm\sqrt3[/tex]
[tex]\tan x=\pm\dfrac1{\sqrt3}[/tex]
This happens on the unit circle whenever [tex]x=\dfrac\pi6,\dfrac{5\pi}6,\dfrac{7\pi}6,\dfrac{11\pi}6[/tex], and more generally for [tex]x=\dfrac\pi6+n\pi[/tex] and [tex]x=-\dfrac\pi6+n\pi[/tex] for integers [tex]n[/tex].
