Y = cos2x - ln |cosx|
Cos2x=sinx-cosx cos²x-sin²x+(cosx-sinx)=0 (cosx-sinx)(cosx+sinx)+(cosx-sinx)=0 (cosx-sinx)(cosx+sinx+1)=0 cosx=sinx => x=π/4+πn cosx+sinx=-1 sin(x+π/4)=-1/√2 x+π/4=(-1)^(n+1) π/4+πk x=-π/4+(-1)^(n+1) π/4+πk