End T11_3.
Section T11_2D.
Context `{T2D:Tarski_2D}.

(* Specifications: *)
Lemma conga__or_out_ts : forall A B C C',
CongA A B C A B C' -> Out B C C' \/ TS A B C C'.
Lemma conga_out_reflectl__out : forall A B C P T T',
~ Out B A C -> CongA P B A P B C -> Out B A T -> ReflectL T T' B P -> Out B C T'.
Lemma col_conga_reflectl__col : forall A B C P T T',
~ Out B A C -> CongA P B A P B C -> Col B A T -> ReflectL T T' B P -> Col B C T'.
Lemma conga2__col : forall A B C P P',
~ Out B A C -> CongA P B A P B C -> CongA P' B A P' B C -> Col B P P'.
Lemma inangle__ex_col_inangle : forall A B C P Q, ~ Out B A C -> InAngle P A B C ->
exists R, InAngle R A B C /\ P <> R /\ Col P Q R.
Lemma acute_perp__one_side : forall P A O B, Acute A O P -> Perp O A B O -> OS O B A P.
End T11_2D.