f(x)=cos(2x-5π/3)+2sin(x-π/4)sin(x+π/4)=cos(2x-2π/3-π)+cosπ/2-cos2x 积化和差公式：sinαsinβ=[-cos(α+β)+cos(α-β)]/2=-cos(2x-2π/3)-cos2x=sin2xsin2π/3-cos2xcos2π/3-cos2x=(...