Помогите с тригонометрией. Умоляю!cos2x-6sinxcosx+3=arccos(-0,5)-2 пи на 3

cos(2x) - 6sin(x)cos(x) + 3 = arccos(-1/2) - 2π/3

cos(2x) - 6sin(x)cos(x) +3 = 0

1 - 2sin(x) - 6sin(x)cos(x) + 3 = 0

2sin(x) + 6cos(x)sin(x) - 4 = 0

Поделим на cos(x):

2tg(x) + 6tg(x) - 4tg(x) - 4 = 0

2tg(x) - 6tg(x) + 4 = 0

tg(x) = 1

tg(x) = 2

--> x = π/4 + πk, x = arctg(2) + πk, k - целое