On Wilker and Huygens type inequalities

Abstract

Trigonometric inequalities, which have been obtained by J. Wilker [11] and C. Huygens [4], have attracted attention of several researchers (see, e.g., [1], [3], [6], [7], [8], [9], [10], [12], [13], [14], [15], [16]). In this paper we offer several refinements and generalizations of these results. Mathematics subject classification (2010): 26D05, 33B10.