tg^2(x) - sin^2(x)-tg^2(x) sin^2(x)=sin^2(x)/cos^2(x)-sin^2(x)-sin^4(x)/cos^2(x)=(sin^2(x)-cos^2(x)*sin^2(x)-sin^4(x))/(cos^2(x)=sin^2(x)(1-cos^2(x)-sin^2(x))/cos^2(x)=sin^2(x)(sin^2(x)-sin^2(x)/cos^2(x)=0
^-степень
