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

Lemma lcos_lg : forall a lp l A B C, Lcos lp l a -> Perp A B B C -> a B A C -> l A C -> lp A B.