cos^2x/sin^2x+cos^2x-1/sin^2x=(cos^2x+cos^2x*sin^2x-sin^2x)/sin^2x=((1-sin^2x+(1-sin^2x)*sin^2x-sin^2x)/sin^2x=(1-sin^2x+sin^2x-sin^4x-sin^2x)/sin^2x=(1-sin^4x-sin^2x)/sin^2x
Замена:sin^2x=t
(1-t^2-t)/t=0
t^2+t-1=0
D1+4=5
sin^2x=(-1+sqrt(5))/2
