Section Cosinus2.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma lcos2_eq_refl : forall l a b, Q_Cong l -> ~ Q_Cong_Null l -> Q_CongA_Acute a -> Q_CongA_Acute b -> Eq_Lcos2 l a b l a b.