proposition: Lemma acosN1 : acos (- 1) = (pi : R).
proof: Proof. by rewrite acosN ?acos1 ?subr0 ?lexx// -subr_ge0 opprK addr_ge0. Qed.
imports: mathcomp(all_ssreflect ssralg ssrint ssrnum matrix) mathcomp(interval rat) mathcomp(mathcomp_extra boolp classical_sets functions) reals ereal nsatz_realtype signed topology normedtype landau sequences derive realfun exp