1)6 sin ^x - 11 cos x - 10 = 0
2) sin ^x + sin x cos x + 6 cos ^ x = 0
3) 4 tg x - 12 ctg + 13 =0

4tgx-12/tgx+13=0; tgx=t; 4t-12/t+13=0; 4t^2+13t-12=0; D=361; t1=0,75; t2=-4; tgx=0,75; tgx=-4; X1=arctg0,75; x2=arctg(-4)