intros; reg.
unfold Rdiv in |- *; rewrite tan_0; ring.
Qed.
(**********)
Definition init_tr (h : TypeSpeed) : Trajectory :=
mkTrajectory
(mkDifferential (fun t : R => (h * t)%R) (init_tr_derivable_x h))
(mkDifferential (fun t : R => 0%R) (init_tr_derivable_y h))
(mkDifferential (fun t : R => 0%R) (init_tr_derivable_y h))
(mkDifferential (fun t : R => 0%R) (init_tr_derivable_y h)) h
(init_tr_cond_x h) (init_tr_cond_y h) init_tr_cond_phi
(init_tr_cond_theta h).

(**********)
Lemma MaxBank_encadr : (0 < MaxBank < PI / 4)%R.
split.