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

Lemma angle_construction_1 : forall A B C A' B' P,
~ Col A B C -> ~ Col A' B' P ->
exists C', CongA A B C A' B' C' /\ OS A' B' C' P.