proposition: Lemma cos_pihalf : cos (pi / 2) = 0.
proof: Proof. exact: pihalf_02_cos_pihalf.2. 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