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-√2,1+√2]
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-√2,1+√2]