sinx的周期是2π,1/2sin2x的周期是π,
它们和函数的周期是2π,
所以y的周期是2π。
假设它的周期是y因为f(x)=sinx+sinxcosx f(x+y)=sinxcosy+cosxsiny+sinxcosxcos^y+cos^xsinycosy-sin^xsinycosy-sinxcosxsin^y=sinxcosy+cosxsiny+sinycosy(cos^x-sin^x)+sinxcosx(cos^y-sin^y) fx=fx+y cosy=0 y=o,2Pi,4Pi 所以周期为二派