Wize University Calculus 1 Textbook > Derivatives

Hyperbolic Functions and their Derivatives

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Hyperbolic Functions and their Derivatives

While Trig Functions are defined for the circle, Hyperbolic Functions are their partners defined for the hyperbola.



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Hyperbolic Function Definitions

sinhx=exex2coshx=ex+ex2tanhx=sinhxcoshx=exexex+ex\displaystyle \boxed{\sinh x=\frac{e^x-e^{-x}}{2} }\hspace{1cm} \boxed{\cosh x=\frac{e^x+e^{-x}}{2}} \hspace{1cm} \boxed{\tanh x=\frac{\sinh x}{\cosh x}=\frac{e^x-e^{-x}}{e^x+e^{-x}}}

cschx=1sinhxsechx=1coshxcothx=coshxsinhx=ex+exexex\displaystyle \boxed{\csch x=\frac{1}{\sinh x}} \hspace{1.3cm} \boxed{\sech x=\frac{1}{\cosh x}} \hspace{1.3cm} \boxed{\coth x=\frac{\cosh x}{\sinh x}=\frac{e^x+e^{-x}}{e^x-e^{-x}}}


Derivatives of Hyperbolic Functions

ddx(sinhx)=coshxddx(coshx)=sinhxddx(tanhx)=sech2x\displaystyle \boxed{\frac{d}{dx}(\sinh x)=\cosh x} \hspace{1cm} \boxed{\frac{d}{dx}(\cosh x)=\sinh x} \hspace{1cm} \boxed{\frac{d}{dx}(\tanh x)=\sech^2 x}

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Example: Hyperbolic Derivatives

Find the derivative of f(x)=sinh(x)cosh(x)f(x) = \sinh(x)\cosh(x)

ddx[sinh(x)cosh(x)]=ddx[sinh(x)]cosh(x)+sinh(x)ddx[cosh(x)]=cosh2(x)+sinh2(x)\begin{aligned} \mydd{\sinh(x)\cosh(x)}{x}[bt] =& \mydd{\sinh(x)}{x}[bt]\cosh(x) + \sinh(x) \mydd{\cosh(x)}{x}[bt] \\ =& \cosh^2(x) + \sinh^2(x) \end{aligned}
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Find the derivative of f(x)=ln(sinh(2x))f(x) = \ln(\sinh(2x))

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