求函数y=cosx+cos(x+π/3),x∈[0,π]的值域 请写下过程,

y=cosx+cos(x+π/3)=cosx+cosxcosπ/3-sinxsinπ/3=3/2cosx-√3/2sinx=√3(√3/2cosx-1/2sinx)=√3cos(x+π/6)∵x∈[0,π]∴x+π/6∈[π/6,7π/6]∴-1≤cos(x+π/6)≤√3/2∴-√3≤√3cos(x+π/6)≤3/2即函数值域为[...