József Sándor

Notes on Number Theory and Discrete Mathematics, ISSN 1310-5132

Volume 19, 2013, Number 1, Pages 73—83

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## Details

### 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

### References

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http://arxiv.org/abs/1105.0859. - Sándor, J. On Huygens’ inequalities and the theory of means, J. Math. & Math. Sci., Vol. 2012, 2012, Article ID 597490.

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## Cite this paper

APASándor, J. (2013). On new refinements of Kober’s and Jordan’s trigonometric inequalities, Notes on Number Theory and Discrete Mathematics, 19(1), 73-83.

ChicagoSándor, József. “On new refinements of Kober’s and Jordan’s trigonometric inequalities.” Notes on Number Theory and Discrete Mathematics 19, no. 1 (2013): 73-83.

MLASándor, József. “On new refinements of Kober’s and Jordan’s trigonometric inequalities.” Notes on Number Theory and Discrete Mathematics 19.1 (2013): 73-83. Print.