1Faculty of Electrical Engineering Mathematics, and Computer Science Delft University of Technology P.O. Box 5031 2600 GA Delft, The Netherlands 2Nesna University College Institute of Teacher Education Mathematics Section 8700 Nesna, Norway
Colloquium Mathematicum, Tome 141 (2015) no. 1, pp. 61-64
The purpose of this paper is to prove the following sequence
of sharp trigonometric inequalities. Let $n\ge 5$ and $0 x \pi$. Then
\[\def\ffrac#1#2{#1/#2}\def\ff{\hskip1pt}
\biggl(\cos\frac{x}{\sqrt{n-1}}\biggr)^{n-1}
\biggl(\frac{\sin\sqrt{\ffrac{5}{n}}\ff x}{\sqrt{\ffrac{5}{n}}\ff x}\biggr)^{\frac{3}{5}n}
\biggl(\cos\frac{x}{\sqrt{n}}\biggr)^n.
\]
Keywords:
purpose paper prove following sequence sharp trigonometric inequalities def ffrac def hskip biggl cos frac sqrt n biggr n biggl frac sin sqrt ffrac sqrt ffrac biggr frac biggl cos frac sqrt biggr
Affiliations des auteurs :
J. B. M. Melissen 
1
;
M. El Ghami 
2
1
Faculty of Electrical Engineering Mathematics, and Computer Science Delft University of Technology P.O. Box 5031 2600 GA Delft, The Netherlands
2
Nesna University College Institute of Teacher Education Mathematics Section 8700 Nesna, Norway
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J. B. M. Melissen; M. El Ghami. A sequence of sharp trigonometric inequalities. Colloquium Mathematicum, Tome 141 (2015) no. 1, pp. 61-64. doi: 10.4064/cm141-1-6