Approximating trigonometric functions by using exponential inequalities

Abstract

Abstract In this paper, some exponential inequalities are derived from the inequalities containing trigonometric functions. Numerical examples show that one can achieve much tighter bounds than those of prevailing methods, which are presented by Cusa, Huygens, Chen and Sándor.

Keywords

• Trigonometric function
• Cusa–Huygens’s inequality
• Chen–Sándor’s inequality
• Monotonically increasing function
• Monotonically decreasing function