Calculus: Early Transcendentals 8th Edition

Published by Cengage Learning
ISBN 10: 1285741552
ISBN 13: 978-1-28574-155-0

Chapter 13 - Section 13.3 - Arc Length and Curvature - 13.3 Exercise - Page 868: 5

Answer

$\frac{1}{27}(13^{3/2}-8)$

Work Step by Step

Given: $r(t)=i+t^2j+t^3k$ ; $0 \leq t \leq 1$ To calculate the length of the curve we will have to use the formula: $L=\int_a^b |r'(t)| dt$ Thus, $r'(t)=\lt 0,2t,3t^2\gt$ and $|r'(t)|=\sqrt {( 2t)^2+(3t^2)^2}dt$ $=\sqrt{ 4t^2+9t^4}$ $L=\int_{0}^1(\sqrt{ 4t^2+9t^4}) dt=\int_{0}^1t(\sqrt{ 4+9t^2}) dt$ $\implies L=\frac{1}{18}(\frac{2}{3}(4+9t^2)^{3/2}|_{0}^1$ $=\frac{1}{27}[(4+9(1)^2)-(4+9(0)^2)]^{3/2}$ $=\frac{1}{27}(13^{3/2}-8)$ Hence, $L=\frac{1}{27}(13^{3/2}-8)$
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