6 tg (2) x -19 tg x+ 3= 0

tg x=t
6t^2-19t+3=0
D=361-72=289=17^2
t1=19-17/12=1/6
t2=19+17/12=3
tg x=1/6
x1=arctg 1/6
tg x=3
x2=arctg 3