设为(x,y)
则√[(x-1)²+(y-1)²]=|x+2y-3|/√(1²+2²)
平方
(x²+y²-2x-2y+2)=(x²+4y²+9+4xy-6x-12y)/5
5x²+5y²-10x-10y+10=x²+4y²+9+4xy-6x-12y
4x²-4xy+y²-4x+2y+1=0