End T11_1.
Section T11_2.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma angle_construction_2 : forall A B C A' B' P,
A <> B -> A <> C -> B <> C -> A' <> B' -> ~ Col A' B' P ->
exists C', CongA A B C A' B' C' /\ (OS A' B' C' P \/ Col A' B' C').