1. 3sin2 x – 7sin x + 4 = 0 2. 6sin2 x – 11cos x – 10 = 0 3. sin2 x + 5sin x cos x + 6cos2 x = 0 4. 4 tg x – 12ctg x + 13 = 0 5. 5 – 8cos2 x = sin 2x 6. 7sin 2x + 9cos 2x = –7

4. 4tgx-12/tgx+13=0
4tgx^2-12+13tgx=0
замена тангенса на а
4а^2-12+13a=0
Дискриминант
169+16x12=19
x1,2=-13+-19/8. x1=5/8 x2=-22/8
x1=arctg5/8+2Пn x2=arctg -11/4+2Пn