y=1/2*cos(πx+π/3)-sin[π-(πx+5π/6)]=1/2*cos(πx+π/3)-sin(-πx+π/6)=1/2*cos(πx+π/3)-cos[π/2-(-πx+π/6)]=1/2*cos(πx+π/3)-cos(πx+π/3)=-1/2*cos(πx+π/3)y递减则cos递增cosx增区间是(2kπ-π,2k...