f(x)=[(1-cosx)+sinx]/sinx=[1-1+2(sin(x/2))^2+2sin(x/2)cos(x/2)]/2sin(x/2)cos(x/2)]=1+tan(x/2)T=π/(1/2)=2π. 其单调区间为(2kπ-π,2kπ+π),k∈Z
