T/2=π/2
T=π=2π/w
w=2
最低M（2π/3,-2)
A=2
f(x)=2sin(2x+φ)=2sin(2(x+φ/2))
2(x+φ/2)=2(2π/3+φ/2)=3π/2
φ=3π/4-2π/3=π/12
f(x)=2sin(2x+π/12)