3sin^2x+10sinxcosx+3cos^2x=0
Там 3sin^2 x....?
3(sin^2 x+cos^2 x)+5sin2x=0 3+5sin2x=0 sin2x=-3/5 2x=(-1)^n-1 arcsin3/5+pi n x=((-1)^n-1 arcsin3/5+pi n)*1/2