f(x)=3sin(2x+φ)的图像向左平移π/6得y=3sin[2(x+π/6）+φ]的图像,后者关于y轴对称,所以π/3+φ=（k+1/2)π,k∈Z,φ∈(0,π/2),所以k=0,φ=π/6,f(x)=3sin(2x+π/6).振幅=3,周期=π,频率=1/π,初相=π/6.y=sinx的...