Section Angles_3.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma is_anga_conga_is_anga : forall A B C A' B' C' a, Ang_Acute A B C a -> CongA A B C A' B' C' -> Ang_Acute A' B' C' a.