Calculus 8th Edition

Published by Cengage
ISBN 10: 1285740629
ISBN 13: 978-1-28574-062-1

Chapter 16 - Vector Calculus - 16.6 Parametric Surfaces and Their Areas - 16.6 Exercises - Page 1161: 48

Answer

$\dfrac{\pi}{2} [\sqrt 2+\ln (1+\sqrt 2)]$

Work Step by Step

$Surface \ Area ; A(S)= \iint_{D} |\dfrac{\partial r}{\partial u} \times \dfrac{\partial r}{\partial v}|=$ and $\iint_{D} dA$ is the area of the region $D$ Now, $\dfrac{\partial r}{\partial u} \times \dfrac{\partial r}{\partial v}=\sin v i-\cos v j +u k$ Therefore, $Surface \ Area ; A(S)=\iint_{D} \sqrt {(\sin v)^2+(-\cos v)^2+u^2} dA$ $=\iint_{D} \sqrt {1+u^2} dA $ $=\int_0^{1} \int_{0}^{\pi} \sqrt {1+u^2} \ dv \ du$ $= \pi \int_0^1 \sqrt {1+u^2} du$ $= \pi [\dfrac{u}{2}\sqrt {u^2+1}+\dfrac{1}{2} \ln (u+\sqrt {u^2+1})]_0^{1}$ $=\dfrac{\pi}{2} [\sqrt 2+\ln (1+\sqrt 2)]$
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