On new refinements of Kober’s and Jordan’s trigonometric inequalities

József Sándor
Notes on Number Theory and Discrete Mathematics, ISSN 1310–5132
Volume 19, 2013, Number 1, Pages 73–83
Full paper (PDF, 174 Kb)

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Authors and affiliations

József Sándor
Babeș-Bolyai University, Department of Mathematics
Str. Kogălniceanu nr. 1, 400084 Cluj-Napoca, Romania

Abstract

This paper deals with some inequalities for trigonometric functions such as the Jordan inequality and Kober’s inequality with refinements. In particular, lower and upper bounds for functions such as (sin x)/x, (1 − cos x)/x and (tan x/2)/x are proved.

Keywords

• Inequalities
• Trigonometric functions
• Jordan’s inequality
• Kober’s inequality
• Convex functions

AMS Classification

• 26D05
• 26D07
• 26D15

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