Calculus (3rd Edition)

Published by W. H. Freeman
ISBN 10: 1464125260
ISBN 13: 978-1-46412-526-3

Chapter 13 - Vector Geometry - 13.1 Vectors in the Plane - Exercises - Page 650: 54

Answer

$\begin{array}{*{20}{c}} {}&{Vector}&{Components}&{Length}\\ {\left( a \right)}&{4{\bf{i}} + 3{\bf{j}}}&{\left( {4,3} \right)}&5\\ {\left( b \right)}&{2{\bf{i}} - 3{\bf{j}}}&{\left( {2, - 3} \right)}&{\sqrt {13} }\\ {\left( c \right)}&{{\bf{i}} + {\bf{j}}}&{\left( {1,1} \right)}&{\sqrt 2 }\\ {\left( d \right)}&{{\bf{i}} - 3{\bf{j}}}&{\left( {1, - 3} \right)}&{\sqrt {10} } \end{array}$

Work Step by Step

We have ${\bf{i}} = \left( {1,0} \right)$ and ${\bf{j}} = \left( {0,1} \right)$. (a) The components are $4{\bf{i}} + 3{\bf{j}} = 4\left( {1,0} \right) + 3\left( {0,1} \right) = \left( {4,3} \right)$ The length: $||4{\bf{i}} + 3{\bf{j}}|| = \sqrt {16 + 9} = 5$. (b) The components are $2{\bf{i}} - 3{\bf{j}} = 2\left( {1,0} \right) - 3\left( {0,1} \right) = \left( {2, - 3} \right)$ The length: $||2{\bf{i}} - 3{\bf{j}}|| = \sqrt {4 + 9} = \sqrt {13} $. (c) The components are ${\bf{i}} + {\bf{j}} = \left( {1,0} \right) + \left( {0,1} \right) = \left( {1,1} \right)$ The length: $||{\bf{i}} + {\bf{j}}|| = \sqrt {1 + 1} = \sqrt 2 $. (d) The components are ${\bf{i}} - 3{\bf{j}} = \left( {1,0} \right) - 3\left( {0,1} \right) = \left( {1, - 3} \right)$ The length: $||{\bf{i}} - 3{\bf{j}}|| = \sqrt {1 + 9} = \sqrt {10} $. In summary: $\begin{array}{*{20}{c}} {}&{Vector}&{Components}&{Length}\\ {\left( a \right)}&{4{\bf{i}} + 3{\bf{j}}}&{\left( {4,3} \right)}&5\\ {\left( b \right)}&{2{\bf{i}} - 3{\bf{j}}}&{\left( {2, - 3} \right)}&{\sqrt {13} }\\ {\left( c \right)}&{{\bf{i}} + {\bf{j}}}&{\left( {1,1} \right)}&{\sqrt 2 }\\ {\left( d \right)}&{{\bf{i}} - 3{\bf{j}}}&{\left( {1, - 3} \right)}&{\sqrt {10} } \end{array}$
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