y=sinx+(√3)cosx用辅助角公式怎么求值域?
y=2[(1/2)sinx+(√3/2)cosx]=2[sinxcos(π/3)+cosxsin(π/3)]=2sin(x+π/3)
由于-1≦sin(x+π/3)≦1,故-2≦2sin(x+π/3)≦2,即值域为[-2,2].