Section Projections.
Context `{T2D:Tarski_2D}.
Context `{TE:@Tarski_euclidean Tn TnEQD}.

Lemma cong_conga3_cong3 :
forall A B C A' B' C',
~ Col A B C ->
Cong A B A' B' ->
CongA_3 A B C A' B' C' ->
Cong_3 A B C A' B' C'.