First solve for the trig function 'cot'
[tex]cot^2 x = \frac{15}{5} = 3[/tex]
Next take the sqrt of both sides (include plus/minus)
[tex]cot x = \pm \sqrt{3}[/tex]
Now take reciprocal of both sides, this will change trig function to 'tan'
(cot = 1/tan)
[tex]tan x = \pm \frac{1}{\sqrt{3}} = \pm \frac{\sqrt{3}}{3}[/tex]
Finally use the unit circle or inverse tan on your calculator to find x.
There will be 4 solutions, one for each quadrant.
[tex]x = \frac{\pi}{6}, \frac{5\pi}{6}, \frac{7\pi}{6}, \frac{11\pi}{6}[/tex]
