intros; reg.
rewrite cos_0; ring.
Qed.

(* Specifications: *)
Lemma init_tr_cond_y :
forall (h : TypeSpeed) (t : R),
derive_pt (fun t : R => 0%R) t (init_tr_derivable_y h t) =
(h * sin ((fun t : R => 0) t))%R.