Hint Resolve
perp_1
perp_2
perp_3
perp_4
perp_5
perp_6
perp_7 : Geom.
Hint Immediate perp_8 perp_9 : Geom.

Lemma not_eq_py_not_zero : forall A B, A<>B -> Py A B A <> 0.
Proof with auto with Geom.