Rational Approximations of Sine and Cosine.

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Bibliographic Details
Title: Rational Approximations of Sine and Cosine.
Authors: Azim, Mashrur1 mashrurazimaornab83@gmail.com, Griffin, Christopher2 griffinch@psu.edu
Source: Mathematics Enthusiast. Oct2025, Vol. 22 Issue 3, p335-342. 7p.
Subject Terms: *Calculus, *Algebra, Trigonometric functions, Sine function, Quartic equations
Abstract: In this paper, we use elementary methods to derive a rational function over the integers to approximate the trigonometric sine function on the interval [0, π/2]. This formula can then be used to derive a quartic polynomial with a root close to π/2, providing an interesting algebraic approximation to this value. A more accurate rational function over the reals is then computed using numerical optimization. This new formula, while more accurate, provides a worse approximation of π/2 in the corresponding quartic equation, showing the trade-offs in local vs. global approximation. This paper is accessible to undergraduates and illustrates a combination of mathematical constructions used in Algebra, Calculus and Numerical Optimization. [ABSTRACT FROM AUTHOR]
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Database: Education Research Complete
Description
Abstract:In this paper, we use elementary methods to derive a rational function over the integers to approximate the trigonometric sine function on the interval [0, π/2]. This formula can then be used to derive a quartic polynomial with a root close to π/2, providing an interesting algebraic approximation to this value. A more accurate rational function over the reals is then computed using numerical optimization. This new formula, while more accurate, provides a worse approximation of π/2 in the corresponding quartic equation, showing the trade-offs in local vs. global approximation. This paper is accessible to undergraduates and illustrates a combination of mathematical constructions used in Algebra, Calculus and Numerical Optimization. [ABSTRACT FROM AUTHOR]
ISSN:15513440
DOI:10.54870/1551-3440.1673