Section Cosinus2.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
Global Instance lcos_morphism :
Proper (EqL ==> EqL ==> eq ==> iff) Lcos.
(*----------------------------------------*)

Lemma lcos3_eq_refl : forall l a b c, Q_Cong l -> ~ Q_Cong_Null l -> Q_CongA_Acute a -> Q_CongA_Acute b -> Q_CongA_Acute c -> Eq_Lcos3 l a b c l a b c.