Ltac ang_instance1 a A B C :=
	assert(tempo_ang:= ang_const a A B);
        match goal with
           |H: Q_CongA a |-  _ => assert(tempo_H:= H);apply tempo_ang in tempo_H; ex_elim tempo_H C
        end;
        clear tempo_ang.

(* Specifications: *)
Lemma ang_sym : forall a A B C, Q_CongA a -> a A B C -> a C B A.
Lemma ang_not_null_lg : forall a l A B C, Q_CongA a -> Q_Cong l -> a A B C -> l A B -> ~ Q_Cong_Null l.
Lemma ang_distincts : forall a A B C, Q_CongA a -> a A B C -> A <> B /\ C <> B.
Lemma anga_sym : forall a A B C, Q_CongA_Acute a -> a A B C -> a C B A.
Lemma anga_not_null_lg : forall a l A B C, Q_CongA_Acute a -> Q_Cong l -> a A B C -> l A B -> ~ Q_Cong_Null l.
Lemma anga_distincts : forall a A B C, Q_CongA_Acute a -> a A B C -> A <> B /\ C <> B.
Lemma ang_const_o : forall a A B P, ~Col A B P -> Q_CongA a -> Q_CongA_nNull a -> Q_CongA_nFlat a -> exists C, a A B C /\ OS A B C P.
Lemma anga_const : forall a A B, Q_CongA_Acute a -> A <> B -> exists C, a A B C.