Cos x*(tg x - cos x)=-sin ^2 x;
Cos x * tg x - cos ^2 x + sin ^2 x=0;
Sin x + 2 sin ^2 x-1=0;
2 sin ^2 x+ sin x-1=0;
Sin x =a;
2a^2+a-1=0;
a1=1/2; a2=-1;
Sinx1=1/2; sinx2=-1;
x1=п/6=30°; x2=3/2 п=270°
9X-289=7X+575
9X-7X=575+289
2X=864:2
X=432
10/7, 22/9, 33/5, 41/15, 59/8