x^2+y^2+2x-2√3y=0……配方x^2+2x+1+y^2-2√3y+3=1+3(x+1)^2+(y-√3)^2=2^2[(x+1)/2]^2+[(y-√3)/2]^2=1令x=2sina-1,y=2cosa+√3x+y=2sina-1+2cosa+√3=2(sina+cosa)+√3-1要求x+y的最小值,即求sina+cosa的最小值si...