f(x)=1-2sin2(x+(π/4))=sin2(x+(π/4))+cos2(x+(π/4))-2sin2(x+(π/4))
=cos2(x+(π/4))-sin2(x+(π/4))=cos[2(x+(π/4))]=cos(2x+π/2)=-sin(2x);
f(π/6)=-sin(2*π/6)=-√3/2.
f(x)=1-2sin2(x+(π/4))=sin2(x+(π/4))+cos2(x+(π/4))-2sin2(x+(π/4))
=cos2(x+(π/4))-sin2(x+(π/4))=cos[2(x+(π/4))]=cos(2x+π/2)=-sin(2x);
f(π/6)=-sin(2*π/6)=-√3/2.