Tangent of i/Proof 2

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Theorem

$\tan i = \paren {\dfrac {e^2 - 1} {e^2 + 1} } i$


Proof

\(\ds \tan i\) \(=\) \(\ds i \tanh 1\) Hyperbolic Tangent in terms of Tangent
\(\ds \) \(=\) \(\ds \paren {\frac {e^1 - e^{-1} } {e^1 + e^{-1} } } i\) Definition of Hyperbolic Tangent
\(\ds \) \(=\) \(\ds \paren {\frac {e^2 - 1} {e^2 + 1} } i\) multiplying denominator and numerator by $e$

$\blacksquare$