Wilker and Huygens type inequalities for mixed trigonometric-hyperbolic functions

Abstract

Motivated by the work of J. Sándor [19], in this paper we establish a new Wilker type and Huygens type inequalities involving the trigonometric and hyperbolic functions. Moreover, in terms of hyperbolic functions, the upper and lower bounds of sin(x)/x and tan(x)/x are given.