- Research Article
- Open Access
On the Superstability Related with the Trigonometric Functional Equation
© Gwang Hui Kim. 2009
Received: 22 August 2009
Accepted: 6 November 2009
Published: 10 November 2009
We will investigate the superstability of the (hyperbolic) trigonometric functional equation from the following functional equations: , , , , which can be considered the mixed functional equations of the sine function and cosine function, of the hyperbolic sine function and hyperbolic cosine function, and of the exponential functions, respectively.
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