Qed.
Definition r_ub (h : TypeSpeed) : R := (h / rho_lb h)%R.
Definition r_lb (h : TypeSpeed) : R := (h / rho_ub h)%R.

(**********)
Lemma tan_lb_MaxBank_pos : (0 < tan_lb_MaxBank)%R.
unfold tan_lb_MaxBank in |- *; unfold Rdiv in |- *;
apply Rmult_lt_reg_l with 10%R.