Multivariable Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 0-53849-787-4
ISBN 13: 978-0-53849-787-9

Chapter 13 - Vector Functions - Review - Exercises - Page 898: 10

Answer

$r(s)=(\dfrac{s}{\sqrt 3}+1) \lt 1, \sin (\ln (\dfrac{s}{\sqrt 3}+1)), \cos (\ln (\dfrac{s}{\sqrt 3}+1)) \gt$

Work Step by Step

Here, $r(t)=\lt e^t , e^t \sin t, e^t \cos t \gt $ and $|r'(t)| = e^t\lt 1, \sin t, \cos t\gt$; $|r'(t)|=e^t\lt 1, \cos t+\sin t, \cos t-\sin t\gt $ Further, $|r'(t)|^2=e^{2t}\lt 1, (\cos t+\sin t)^2, (\cos t-\sin t)^2 \gt=3e^{2t} $ $\implies |r'(t)|=\sqrt 3e^{t} $ We need to solve for $t$ $e^t=\dfrac{s}{\sqrt 3}+1$ and $t=\ln (\dfrac{s}{\sqrt 3}+1)$ Hence, we have $r(s)=(\dfrac{s}{\sqrt 3}+1) \lt 1, \sin (\ln (\dfrac{s}{\sqrt 3}+1)), \cos (\ln (\dfrac{s}{\sqrt 3}+1)) \gt$
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