G(x,y),P(x1,y1),Q(x2,y2)
x=(x1+x2+1)/3,y=(y1+y2)/3
x1+x2=3x-1,y1+y2=3y
而PQ中点M((x1+x2)/2,(y1+y2)/2)与O的距离的平方为3
所以(x1+x2)^2+(y1+y2)^2=12
(3x-1)^2+9y^2=12
G(x,y),P(x1,y1),Q(x2,y2)
x=(x1+x2+1)/3,y=(y1+y2)/3
x1+x2=3x-1,y1+y2=3y
而PQ中点M((x1+x2)/2,(y1+y2)/2)与O的距离的平方为3
所以(x1+x2)^2+(y1+y2)^2=12
(3x-1)^2+9y^2=12