proposition: Lemma sin_bound : forall (a : R) (n : nat), 0 <= a -> a <= PI -> sin_approx a (2 * n + 1) <= sin a <= sin_approx a (2 * (n + 1)).
proof: Proof. intros a n a0 api; apply pre_sin_bound. - assumption. - apply Rle_trans with (1:= api) (2 := PI_4). Qed.
imports: Rbase Rfunctions SeqSeries Rtrigo_fun Rtrigo_def Rtrigo_alt Cos_rel Cos_plus ZArith_base Zcomplements Lia Lra Ranalysis1 Rsqrt_def PSeries_reg