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偶函数则f(x)=f(-x)sin(ωx+Xw)=sin(-ωx+X)sin(ωx+X)+sin(ωx-X)=0---------(1)由公式sin(a)+sin(b) = 2sin[(a+b)/2]cos[(a-b)/2] (1)得|:2sin[wx]cos[-X]=0由于w≠0,故X=2kπ+π/2,k=±1、2、3...取X=π/2∵其图象上相临两对称轴之间的距离为π，即周期T/2=π,2π/ω=T,得ω=1,推出f(x)=sin(x+π/2)=-cosx2)sina+f(a)=2/3sin(x+π/2)+sinx=2/3 ,即:cosx+sinx=2/3,因为1+tanx=... |
