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

Lemma acute_comp_not_acute : forall A B C D, Bet A B C -> Acute A B D -> ~ Acute C B D.