La Derivada del Coseno

2007/03/08 by Joseph F. Johnson, Johnson, Joseph F.
Mathematics · #97C90 #FOS: Mathematics #General Mathematics (math.GM) #math.GM #msc:97C90

paper · pdf · doi:10.48550/arxiv.math/0703239

One page, two figures

arxiv created 2007/03/09 · arxiv updated 2009/12/01

Abstract

The simplest rigourous, non-circular proof that d(cos x) = -sen x. Some details omitted if the gap is intuitive, nevertheles, each gap is easily filled, rigourously. As Ehrenpreis and others have pointed out, the usual text book `proof' is circular, since it assumes the area of circular sectors is already known. Various Cours d'Analyse tomes (Hermite, Jordan, etc.) have correct proofs which, however, are more difficult.

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