Thank you for your post. Whilst I don't disagree with anything you have said, I still have a problem accepting the proposition: $$Mx+B = \pm m \sqrt{ x^{2} + y^{2} } \Rightarrow (x,y,z) \in P \cap C. $$ In fact, suppose $(x,y,z) \in P \cap C,$ then by that very proposition it follows that...