Advances in Difference Equations
Volume 2007 (2007), Article ID 90405, 10 pages
doi:10.1155/2007/90405
Research Article
On the Stability of Trigonometric Functional Equations
Department of Mathematics, Kangnam University, Youngin, Gyeonggi 446-702, South Korea
Received 17 February 2007; Accepted 5 October 2007
Academic Editor: Bing Gen Zhang
Copyright © 2007 Gwang Hui Kim. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
The aim of this paper is to study the superstability related to the d'Alembert, the Wilson, the sine functional equations for the trigonometric functional equations as follows: f(x+y)−f(x−y)=2f(x)g(y),f(x+y)−f(x−y)=2g(x)f(y).