d=[Ax0+By+c]/√(a^2+b^2)
(x-y)/√2=(2x+y)/√5
(√8-√5)x+(√5+√2)y=0
到直线X-Y=0与2X+Y=0的距离相等的点的轨迹方程是
(√8-√5)x+(√5+√2)y=0