January 2001
Let be six distinct points on the plane.
and are collinear, likewise and .
Let be the intersection of the lines and .
Let be the intersection of the lines and .
Let be the intersection of the lines and .
Then and are collinear.
Let be six distinct points on the plane.
and are collinear, likewise and .
Let be the intersection of the lines and .
Let be the intersection of the lines and .
Let be the intersection of the lines and .
Then and are collinear.