Require Export GeoCoq.Tarski_dev.Ch14_sum.
Section T14_prod.
Context `{T2D:Tarski_2D}.
Context `{TE:@Tarski_euclidean Tn TnEQD}.

Lemma project_pj : forall P P' A B X Y, Proj P P' A B X Y -> Pj X Y P P'.