由于：x^2+(y-1)^2=1则利用圆的参数方程设：x=cosa,y=1+sina (a属于R)则：x+y=cosa+1+sina=(sina+cosa)+1=√2sin(a+π/4)+1 (辅助角公式)由于：a属于R则：(a+π/4)属于R则：sin(a+π/4)属于[-1,1]则：(x+y)属于[1-√...