y=sin（x+π/6）+cosx
=sinxcosπ/6+cosxsinπ/6+cosx
=√3/2sinx+1/2cosx+cosx
=√3/2sinx+3/2cosx
=√3(1/2sinx+√3/2cosx)
=√3(sinxcosπ/3+cosxsinπ/3）
=√3sin(x+π/3)