1 - 4 sin 2 x + 6 cos ^2 x = 0

Решение. Sin2x – 5sinx cosx + 6cos2x = 0 Делим обе части уравнения на cos2x tg2x – 5tgx + 6 = 0 tgx = t t2 – 5t + 6=0 t1 = 3 t2 = 2 tgx = 3 tgx = 2 x= arctg3 + πk, k Z x= arctg2 + πn, n Z Ответ: x = arctg3 + πk, х = arctg2 + πn, n, k Z