y=sin(π/4-3x)+√3cos(π/4-3x)=2sin(π/4-3x+π/3)=2sin(7π/12-3x)=2sin(π-7π/12+3x)
=2sin(3x+5π/12)
故T=2π/3为什么会等于2sin（π/4-3x+π/3）辅助角公式，y=sin(π/4-3x)+√3cos(π/4-3x)=2[sin(π/4-3x)/2+√3cos(π/4-3x)/2]