y’=1/2+cosx,y’>0, cosx>-1/2, 2kπ-2π/3y’<0, cosx<-1/2, 2kπ+2π/3所以增区间为[2kπ-2π/3,2kπ+2/3],k∈Z,减区间为[2kπ+2π/3,2kπ+4/3],k∈Z.
