Difference between revisions of "Sinh"

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File:Complex Sinh.jpg|[[Domain coloring]] of [[analytic continuation]] of $\sinh$.
 
File:Complex Sinh.jpg|[[Domain coloring]] of [[analytic continuation]] of $\sinh$.
 
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<center>{{:Hyperbolic trigonometric functions footer}}</center>
 
<center>{{:Hyperbolic trigonometric functions footer}}</center>

Revision as of 05:30, 20 March 2015

The hyperbolic sine function is defined by $$\mathrm{sinh}(z)=\dfrac{e^z-e^{-z}}{2}.$$

Properties

Theorem

The following formula holds: $$\dfrac{\mathrm{d}}{\mathrm{d}z} \sinh(z) = \cosh(z),$$ where $\sinh$ denotes the hyperbolic sine and $\cosh$ denotes the hyperbolic cosine.

Proof

From the definition, $$\sinh(z) = \dfrac{e^z-e^{-z}}{2},$$ and so using the derivative of the exponential function, the linear property of the derivative, the chain rule, and the definition of the hyperbolic cosine, $$\dfrac{\mathrm{d}}{\mathrm{d}z} \sinh(z)=\dfrac{e^z + e^{-z}}{2}=\cosh(z),$$ as was to be shown. █

References

<center>Hyperbolic trigonometric functions
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