(1+cos2x)²-2cos2x-1=1+2cos(2x)+cos²(2x)-2cos(2x)-1=cos²(2x)=[cos²(x)-sin²(x)]²=[cos(x)-sin(x)]² * [cos(x)+sin(x)]² sin(π/4+x)=sin(π/4)cos(x)+cos(π/4)sin(x)=[...