unfold Col in |- *.
intros...
Qed.

(* Specifications: *)
Theorem col_2 : forall A B C : Point, Col A B C -> Col A C B.
Proof with uniformize_signed_areas;Geometry.
Theorem col_3 : forall A B C : Point, Col A B C -> Col B C A.
Proof with uniformize_signed_areas;Geometry.
Theorem col_4 : forall A B C : Point, Col A B C -> Col C B A.
Proof with uniformize_signed_areas;Geometry.
Theorem col_5 : forall A B C : Point, Col A B C -> Col C A B.
Proof with uniformize_signed_areas;Geometry.