Question

Find the x-values that are solutions of the equation 5cot^2x-15=0

Answer 1

First solve for the trig function 'cot'
$cot^2 x = \frac{15}{5} = 3$

Next take the sqrt of both sides (include plus/minus)
$cot x = \pm \sqrt{3}$

Now take reciprocal of both sides, this will change trig function to 'tan'
(cot = 1/tan)

$tan x = \pm \frac{1}{\sqrt{3}} = \pm \frac{\sqrt{3}}{3}$

Finally use the unit circle or inverse tan on your calculator to find x.
There will be 4 solutions, one for each quadrant.

$x = \frac{\pi}{6}, \frac{5\pi}{6}, \frac{7\pi}{6}, \frac{11\pi}{6}$