A characterization of the tangent function (Q919116)
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scientific article; zbMATH DE number 4158992
| Language | Label | Description | Also known as |
|---|---|---|---|
| English | A characterization of the tangent function |
scientific article; zbMATH DE number 4158992 |
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A characterization of the tangent function (English)
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1989
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Real-valued functions T satisfying the identity \(T(u+v)=[T(u)+T(v)]/[1- T(u)T(v)]\) are studied. It is proved that the tangent function is the only such function having domain \(\{x:x\quad real,\quad x\neq \pi /2+m\pi,\quad m\quad an\quad integer\}\) and satisfying \(T'(0)=1\).
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tangent function
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