The Prosthaphaeretic Slide Rule: A Mechanical Multiplication Device Based on Trigonometric Identities
Sher, David B., Nataro, Dean C., Mathematics and Computer Education
The typical precalculus book contains the obscure trigonometric identities known as the product-to-sum formulas [1, p. 470]. They usually get short treatment (or none) in a precalculus course because they are so rarely used. This is unfortunate since they have an interesting history. Before the invention of logarithms they were used to perform multiplications and divisions by a process known as prosthaphaeresis. Since the slide rule is a computational device based on logarithms, the authors wondered if a similar device based on prosthaphaeresis could be constructed. It can. We call it the "prosthaphaeretic slide rule".
Formula 3 is …
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Publication information: Article title: The Prosthaphaeretic Slide Rule: A Mechanical Multiplication Device Based on Trigonometric Identities. Contributors: Sher, David B. - Author, Nataro, Dean C. - Author. Journal title: Mathematics and Computer Education. Volume: 38. Issue: 1 Publication date: Winter 2004. Page number: 37+. © Mathematics and Computer Education Winter 2009. Provided by ProQuest LLC. All Rights Reserved.
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