Calculus: Early Transcendentals (2nd Edition)

Published by Pearson
ISBN 10: 0321947347
ISBN 13: 978-0-32194-734-5

Chapter 11 - Vectors and Vector-Valued Functions - 11.4 Cross Products - 11.4 Exercises - Page 797: 22

Answer

\[\sqrt {38} \]

Work Step by Step

\[\begin{gathered} {\mathbf{u}} = - 3{\mathbf{i}} + 2{\mathbf{k}},\,\,\,{\mathbf{v}} = {\mathbf{i}} + {\mathbf{j}} + {\mathbf{k}} \hfill \\ {\text{The area of the parallelogram is given by }}\left| {{\mathbf{u}} \times {\mathbf{v}}} \right| \hfill \\ {\mathbf{u}} \times {\mathbf{v}} = \left| {\begin{array}{*{20}{c}} {\mathbf{i}}&{\mathbf{j}}&{\mathbf{k}} \\ { - 3}&0&2 \\ 1&1&1 \end{array}} \right| \hfill \\ {\mathbf{u}} \times {\mathbf{v}} = \left| {\begin{array}{*{20}{c}} 0&2 \\ 1&1 \end{array}} \right|{\mathbf{i}} - \left| {\begin{array}{*{20}{c}} { - 3}&2 \\ 1&1 \end{array}} \right|{\mathbf{j}} + \left| {\begin{array}{*{20}{c}} { - 3}&0 \\ 1&1 \end{array}} \right|{\mathbf{k}} \hfill \\ {\mathbf{u}} \times {\mathbf{v}} = \left( { - 2} \right){\mathbf{i}} - \left( { - 3 - 2} \right){\mathbf{j}} + \left( { - 3} \right){\mathbf{k}} \hfill \\ {\mathbf{u}} \times {\mathbf{v}} = - 2{\mathbf{i}} + 5{\mathbf{j}} - 3{\mathbf{k}} \hfill \\ {\text{Area}} = \left| {{\mathbf{u}} \times {\mathbf{v}}} \right| \hfill \\ {\text{Area}} = \left| { - 2{\mathbf{i}} + 5{\mathbf{j}} - 3{\mathbf{k}}} \right| \hfill \\ {\text{Area}} = \sqrt {{{\left( { - 2} \right)}^2} + {{\left( 5 \right)}^2} + {{\left( { - 3} \right)}^2}} \hfill \\ {\text{Area}} = \sqrt {4 + 25 + 9} \hfill \\ {\text{Area}} = \sqrt {38} \hfill \\ \end{gathered} \]
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