Difference between revisions of "Gudermannian"

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The Gudermannian $\mathrm{gd}$ is defined for $x \in \mathbb{R}$ by the formula
 
The Gudermannian $\mathrm{gd}$ is defined for $x \in \mathbb{R}$ by the formula
 
$$\mathrm{gd}(x) = \displaystyle\int_0^x \dfrac{1}{\cosh t} dt$$
 
$$\mathrm{gd}(x) = \displaystyle\int_0^x \dfrac{1}{\cosh t} dt$$
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 +
=Properties=
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<div class="toccolours mw-collapsible mw-collapsed">
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<strong>Theorem:</strong> The following formula holds:
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$$\sin(\mathrm{gd}(x))=\tanh(x),$$
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where $\sin$ denotes the [[sine]], $\mathrm{gd}$ denotes the [[Gudermannian]], and $\tanh$ denotes the [[tanh|hyperbolic tangent]].
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<div class="mw-collapsible-content">
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<strong>Proof:</strong> █
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</div>
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</div>
  
 
<center>{{:*-integral functions footer}}</center>
 
<center>{{:*-integral functions footer}}</center>

Revision as of 22:42, 25 August 2015

The Gudermannian $\mathrm{gd}$ is defined for $x \in \mathbb{R}$ by the formula $$\mathrm{gd}(x) = \displaystyle\int_0^x \dfrac{1}{\cosh t} dt$$

Properties

Theorem: The following formula holds: $$\sin(\mathrm{gd}(x))=\tanh(x),$$ where $\sin$ denotes the sine, $\mathrm{gd}$ denotes the Gudermannian, and $\tanh$ denotes the hyperbolic tangent.

Proof:

<center>$\ast$-integral functions
</center>