已知函数f(x)=根号3sin(wx+φ)-cos(wx+φ)(0

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已知函数f(x)=根号3sin(wx+φ)-cos(wx+φ)(0

已知函数f(x)=根号3sin(wx+φ)-cos(wx+φ)(0
已知函数f(x)=根号3sin(wx+φ)-cos(wx+φ)(0

已知函数f(x)=根号3sin(wx+φ)-cos(wx+φ)(0
(1)f(x)=根号3sin(wx+φ)-cos(wx+φ)=2Sin(wx+φ-π/6)
由于是偶函数,即f(x)=f(-x)
即2Sin(wx+φ-π/6)=2Sin(-wx+φ-π/6)
即SinwxCos(φ-π/6)+CoswxSin(φ-π/6)=-SinwxCos(φ-π/6)+CoswxSin(φ-π/6)
即SinwxCos(φ-π/6)=0
又Sinwx不恒等于0,所以Cos(φ-π/6)=0
又0

为什么Sinwx不恒等于0,解释得详细一点

f(x)=√3sin(wx+ч)-cos(wx+ч)=2[cos(π/6)sin(wx+ч)-sin(π/6)cos(wx+ч)=2sin(wx+ч-π/6),