3ctq²(3π/2 +x/3) -2tq(x/3) =1;
3tq²(x/3) -2tq(x/3) - 1 =0 ;
* * кв. уравнения относительно tq(x/3),можно и пров. замену t =tq(x/3) *
D/4 =1 -3(-1) =4 =2² .
tq(x/3) =(1± 2)/3.
[ tq(x/3) = -1/3 ; tq(x/3) =1. (совокупность)
[ x/3 = -arctq(1/3)+π*n , x/3 =π/4 +π*n , n ∈ Z.
[ x = -3arctq(1/3)+3π*n , x =3π/4 +3π*n , n ∈ Z.
ответ : -3arctq(1/3)+3π*n , x =3π/4 +3π*n , n ∈ Z.