Section T10_1.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma l10_12 : forall A B C A' B' C',
Per A B C -> Per A' B' C' ->
Cong A B A' B' -> Cong B C B' C' ->
Cong A C A' C'.