Abstract

We give a short proof to characterize the cases when arccos(√r), the arccosine of the squareroot of a rational number r ∈ [0, 1], is a rational multiple of π: This happens exactly if r is an integer multiple of 1/4. The proof relies on the well-known recurrence relation for the Chebyshev polynomials of the first kind.

Details

Title
Rational values of the arccosine function
Author
Varona, Juan 1 

 Universidad de La Rioja 
Pages
319-322
Publication year
2006
Publication date
2006
Publisher
De Gruyter Brill Sp. z o.o., Paradigm Publishing Services
ISSN
18951074
e-ISSN
16443616
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2545261051
Copyright
© 2006. This work is published under http://creativecommons.org/licenses/by-nc-nd/3.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.