There are 6 distinct points, such that there between every four points there are three collinear.
Prove that at least five of these given points belong to one line.
If we have points A,B,C,D,E,F then
between ABCD there is one point, lets say point D that doesn't belong to line ABC.
Now between ABDE, AB is not collinear with D so ABE must be collinear.
Between ABDF, ABF is collinear.
So we have ABCEF are collinear.
Is this proof correct?