Using the double angle formula for tan and that cot is 1/tan:
2tan/(1-tan2) - 1/tan = 0 ( the 4 times requires that this part be zero as the 4 cannot make the equation equal to zero.
2tan2x = 1- tan2x.
tan2x = 1/3
tanx = +/- 1/sqrt(3) x = pi/6, 5pi/6, 7pi/6, 11pi/6
Also there is a weirdness in that both terms go to 0 when tanx goes to +/- infinity. This happens at pi/2, 3pi/2
If you plot this equation on DESMOS you can see what the function looks like and that the zeroes are clear.