y=sin²x+sinx+cosx+2=(1-cos2x)/2+√2sin(x+л/4)+2=(1/2)*sin(2x+л/2)+ √2*sin(x+л/4)+5/2；=(1/2)*sin(2θ)+ √2*sin(θ)+5/2；……θ=x+л/4；对上式两端求导并令导数等于0：y’=cos(2θ)+ √2*cosθ=0；...