解由fx=-f(x+π)知T=2π又由T=2π/w=2π即w=1故fx=sin(x+φ)又由f0=1/2则sin(0+φ)=1/2即φ=π/6故fx=sin(x+π/6)故gx=2cos(wx+φ)=2cos(x+π/6)由x属于(0,π/2)知2x属于(0,π)即2x+π/6属于(π/6,7π/6)故2x+π/6=π时,函数gx=2cos(wx+φ)=2cos(x+π/6)有最小值y=2cosπ=2×(-1)=-2.