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)=1-1/[cos(x/2)+1]
因为f(x)=f(-x),所以偶函数.2pi/(1/2)=4pi,这的1/2是cos中x的系数
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)=1-1/[cos(x/2)+1]
因为f(x)=f(-x),所以偶函数.2pi/(1/2)=4pi,这的1/2是cos中x的系数