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问题: 化简f(x)=sinx/sinx+2sinx/2

解答:

f(x)= sinx/[sinx+2sin(x/2)]
  = 2sin(x/2)cos(x/2)/[2sin(x/2)cos(x/2)+2sin(x/2)]
  = cos(x/2)/[cos(x/2)+1]
=cos(x/2)+1-1/[cos(x/2)+1]
=1-(1/[cos(x/2)+1])

周期就是函数cos(x/2)的周期 圆周率的4倍