√[2+2sin(2π-θ)-cos^2(π+θ)]=√[2-2sinθ-cos^2θ]=√[2-2sinθ-(1-sin^2θ)]=√(sin^2θ-2sinθ+1)=√(sinθ-1)^2=1-sinθ朋友,你刚刚采纳的那个没做完,我这个才是对的.因为1＞sinθ,所以|sinθ-1|=1-sinθ而...