proposition: Lemma tan_MaxBank_pos : (0 < tan MaxBank)%R.
proof: Proof. apply Rlt_trans with tan_lb_MaxBank. unfold tan_lb_MaxBank in |- *; unfold Rdiv in |- *; apply Rmult_lt_reg_l with 10%R. prove_sup. rewrite Rmult_0_r; rewrite <- Rmult_comm; repeat rewrite Rmult_assoc; rewrite <- Rinv_l_sym. prove_sup. discrR. apply tan_MaxBank_lb. Qed.
imports: Reals pi_ineq