Calculus 10th Edition

Published by Brooks Cole
ISBN 10: 1-28505-709-0
ISBN 13: 978-1-28505-709-5

Chapter 5 - Logarithmic, Exponential, and Other Transcendental Functions - 5.8 Exercises - Page 390: 15

Answer

$\mathrm{c}\mathrm{s}\mathrm{c}\mathrm{h}\ x=\displaystyle \frac{2}{3}$ $\displaystyle \cosh x=\frac{\sqrt{13}}{2} \qquad $ $\mathrm{s}\mathrm{e}\mathrm{c}\mathrm{h}\ x=\displaystyle \frac{2}{\sqrt{13}}$ $\displaystyle \tanh x=\frac{3\sqrt{13}}{13} $ $\displaystyle \coth x=\frac{\sqrt{13}}{3}$

Work Step by Step

$\displaystyle \sinh x=\frac{3}{2}$ $\begin{align*} \cosh^{2}x-\sinh^{2}x&=1\\ \cosh^{2}x&=1+\sinh^{2} \\ \cosh x&=\sqrt{1+(3/2)^{2}} \\ &=\sqrt{13/4} \\\\ & =\displaystyle \frac{\sqrt{13}}{2} \end{align*}$ $\displaystyle \sinh x=\frac{3}{2} \qquad $ $\mathrm{c}\mathrm{s}\mathrm{c}\mathrm{h}\ x=\displaystyle \frac{1}{\sinh x}=\frac{2}{3}$ $\displaystyle \cosh x=\frac{\sqrt{13}}{2} \qquad $ $\mathrm{s}\mathrm{e}\mathrm{c}\mathrm{h}\ x=\displaystyle \frac{2}{\sqrt{13}}$ $\displaystyle \tanh x=\frac{\sinh x}{\cosh x} =\frac{\frac{3}{2}}{\frac{\sqrt{13}}{2}} = \frac{3}{\sqrt{13}}\cdot\frac{\sqrt{13}}{\sqrt{13}} =\frac{3\sqrt{13}}{13} $ $\displaystyle \coth x=\frac{1}{\tanh x}=\frac{\sqrt{13}}{3}$
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