Solve

4sin(x)^2*tan(x)=tan(x) = {x=0, x=-(((pi)/6)), x=((pi)/6)}

I think. Probably not though. :|

I don't understand your answer, I need angles, like 30º, 45º, etc.

4 sin^2 x tan x = tan x     subtract tan x from both sides

4sin^2x tanx - tan x = 0      factor  out tan x

tanx [ 4sin^2x - 1 ] = 0

Set both factors to 0

tan x = 0     and this happnes at  [ 0 ± n 180 ] degrees    where ni is an integer

4sin^2 x = 1      divide both sides by 4

sin^2x  = 1/4      take ± roots of both sides

sinx = ± √[ 1/4]   = ± 1/2   and this happens at [ 30 ± n 180] degrees  and at [ 150 ± n 180] degrees     where n is an integer

Here's a graph : https://www.desmos.com/calculator/aeoqwikiz7