3 sin^2 x-2 sin x cos x - cos^2 x = 2

3 sin^2 x-2 sin x cos x - cos^2 x = 2

3 sin^2 x-2 sin x cos x - cos^2 x = 2 * (Sin^2x + Cos^2x)

3 sin^2 x-2 sin x cos x - cos^2 x = 2Sin^2x + 2Cos^2x

Sin^2x - 2SinxCosx - 3Cos^2x = 0 | : Cos^2x

tg^2x - 2tgx - 3 = 0

tgx = t

t ² - 2t - 3 = 0

по т. Виета корни - 1 и 3

а) tgx = - 1

x = - π/4 + πk, k ∈Z

б) tgx = 3

x = arctg3 + πn, n ∈Z