Showing that the vertices of two self-polar triangles with respect to a conic are in general position I am reading up posts on projective geometry, and I came across this one talking about self-polar triangles with respect to a conic. I am trying to prove that the vertices of two self-polar triangles are in general position. I do not understand the part of his proof where he says

neither three points from A,B,C,P,Q,R are colinear.

Could someone explain me why this is the case? For example, why could not $A$, $B$ and $P$ be colinear? I tried to prove by contradiction (assuming that $A,B,P$ are colinear and trying to come to a contradiction), but I am not able to.
(I would have commented on his post, but I do not have enough reputation...)
Thank you.
Edit: I actually think it is wrong. (If now I am wrong, please tell me). Here is an illustration on Geogebra.
The triangles $DEF$ and $GHI$ are self-polar with respect to the ellipse, but they are not in general position.
I would love to have some feedback on my craziness.

You're right. There's nothing to stop 3 points from being collinear, but in that case the six points will lie on a degenerate conic. The statement to be proven did not stipulate that they had to lie on a non-degenerate conic.  I've upvoted your question, which should give you enough reputation to comment on the other post. 
