sin²(π-α)-sin(0.5π+2)×cos(0.5π-2)+2=sin²(α)-cos2sin2+2=(14/5)-cos2sin2tan(π+α)=2=tanα ,2cosα=sinα ,4cos^2(α)=sin^2(α) ,4-4sin^2(α)=sin^2(α)sin^2(α)=4/5