Hint Resolve l8_2 : perp.
Ltac Perp := auto with perp.
Section T8_2.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma l8_6 : forall A B C A', Per A B C -> Per A' B C -> Bet A C A' -> B=C.
End T8_2.