2*cos^2wx-1=cos2wx 2*sinwx*coswx=sin2wx
所以 cos^2wx=(cos2wx+1)/2 sinwx*coswx=sin2wx/2
y=√sin2wx/2-(cos2wx+1)/2
y=√sin2wx/2-cos2wx/2-1/2
y=√((1/(√2))(√2sin2wx/2-√2cos2wx/2))-1/2
y=√((1/(√2))(sin(2wx-45)))-1/2
y=√((√2)(sin(2wx-45))-1)/2
2*cos^2wx-1=cos2wx 2*sinwx*coswx=sin2wx
所以 cos^2wx=(cos2wx+1)/2 sinwx*coswx=sin2wx/2
y=√sin2wx/2-(cos2wx+1)/2
y=√sin2wx/2-cos2wx/2-1/2
y=√((1/(√2))(√2sin2wx/2-√2cos2wx/2))-1/2
y=√((1/(√2))(sin(2wx-45)))-1/2
y=√((√2)(sin(2wx-45))-1)/2