intro m; unfold mod_ in |- *; unfold rest in |- *...
Qed.
Definition trkrate (phi : Bank) : R :=
toDeg (g * (tand phi / v intruderSpeed)).

Lemma cond1_0 : (- toDeg MaxBank <= 0)%R.
left; rewrite <- Ropp_0; apply Ropp_lt_gt_contravar; unfold toDeg in |- *;
repeat simple apply Rmult_lt_0_compat.