Section Cosinus2.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma lcos_eql_lcos : forall lp1 l1 lp2 l2 a, EqL lp1 lp2 -> EqL l1 l2 -> Lcos lp1 l1 a -> Lcos lp2 l2 a.
Global Instance lcos_morphism :
Proper (EqL ==> EqL ==> eq ==> iff) Lcos.