Section Quadrilateral.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
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Lemma col_cong_mid1 : forall A B C D, A <> D -> Col A B C -> Col A B D -> Cong A B C D -> Cong A C B D
-> exists M, Midpoint M A D /\ Midpoint M B C.