Difference between revisions of "Selftest: Dot product"
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− | {{ExerciseNavigation|previous=[[Selftest:Simple arithmetic operations|Simple arithmetic operations]]| | + | {{ExerciseNavigation|previous=[[Selftest: Simple arithmetic operations|Simple arithmetic operations]]|chapter=[[Vector algebra]]|article=[[Dot product]]|next=[[Selftest: Cross product|Cross product]]}} |
− | <quiz> | + | <quiz display=simple> |
{'''What is the result of dor product of <math>\vec{\mathbf{a}}</math> and <math>\vec{\mathbf{b}}</math>?''' | {'''What is the result of dor product of <math>\vec{\mathbf{a}}</math> and <math>\vec{\mathbf{b}}</math>?''' | ||
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+ 15 | + 15 | ||
− | ||The result of the dot product is a ''scalar'' value. In this case the easiest way to compute the dot product is using the angle between the two vectors:<math>\vec{\mathbf{a}} \cdot \vec{\mathbf{b}} = a b \cos \alpha</math>. The angle is 0° and so the cosine is 1. Further information: see [[Dot product]]. | + | ||The result of the dot product is a ''scalar'' value. In this case the easiest way to compute the dot product is using the angle between the two vectors: <math>\vec{\mathbf{a}} \cdot \vec{\mathbf{b}} = a b \cos \alpha</math>. The angle is 0° and so the cosine is 1. Further information: see [[Dot product]]. |
{'''What is the result of dor product of <math>\vec{\mathbf{a}}</math> and <math>\vec{\mathbf{b}}</math>?''' | {'''What is the result of dor product of <math>\vec{\mathbf{a}}</math> and <math>\vec{\mathbf{b}}</math>?''' | ||
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+ 0 | + 0 | ||
− | ||The result of the dot product is a ''scalar'' value. In this case the easiest way to compute the dot product is using the angle between the two vectors:<math>\vec{\mathbf{a}} \cdot \vec{\mathbf{b}} = a b \cos \alpha</math>. The angle is 90° and so the cosine is 0. Further information: see [[Dot product]]. | + | ||The result of the dot product is a ''scalar'' value. In this case the easiest way to compute the dot product is using the angle between the two vectors: <math>\vec{\mathbf{a}} \cdot \vec{\mathbf{b}} = a b \cos \alpha</math>. The angle is 90° and so the cosine is 0. Further information: see [[Dot product]]. |
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+ -15 | + -15 | ||
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− | ||The result of the dot product is a ''scalar'' value. In this case the easiest way to compute the dot product is using the angle between the two vectors:<math>\vec{\mathbf{a}} \cdot \vec{\mathbf{b}} = a b \cos \alpha</math>. The angle is 180° and so the cosine is -1. Further information: see [[Dot product]]. | + | ||The result of the dot product is a ''scalar'' value. In this case the easiest way to compute the dot product is using the angle between the two vectors: <math>\vec{\mathbf{a}} \cdot \vec{\mathbf{b}} = a b \cos \alpha</math>. The angle is 180° and so the cosine is -1. Further information: see [[Dot product]]. |
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− | {''' | + | {'''Please solve the following exercise:''' |
| type="{}" } | | type="{}" } | ||
<math>\begin{pmatrix} 2 \\ 3 \\ 5 \end{pmatrix}\cdot \begin{pmatrix} -3 \\ 6 \\ 4 \end{pmatrix}=</math>{ 32 } | <math>\begin{pmatrix} 2 \\ 3 \\ 5 \end{pmatrix}\cdot \begin{pmatrix} -3 \\ 6 \\ 4 \end{pmatrix}=</math>{ 32 } | ||
− | || | + | ||There are two possibilities to compute the dot product. Either the component representation <math>\vec{\mathbf{a}}\cdot\vec{\mathbf{b}} = \begin{pmatrix}a_1 \\ a_2 \\ a_3 \end{pmatrix}\cdot\begin{pmatrix}b_1 \\ b_2 \\ b_3 \end{pmatrix}=a_1b_1+a_2b_2+a_3b_3</math> is used or the angle between the vectors: <math>\vec{\mathbf{a}} \cdot \vec{\mathbf{b}} = a \vec{\mathbf{e}}_{a} \cdot \vec{\mathbf{e}}_{b} = a b \cos \alpha </math>. |
− | {''' | + | {'''Please solve the following exercise:''' |
| type="{}" } | | type="{}" } | ||
<math>\begin{pmatrix} 1 \\ 2 \\ 3 \end{pmatrix}\cdot \begin{pmatrix} -4 \\ 1 \\ -6 \end{pmatrix}=</math>{ -20 } | <math>\begin{pmatrix} 1 \\ 2 \\ 3 \end{pmatrix}\cdot \begin{pmatrix} -4 \\ 1 \\ -6 \end{pmatrix}=</math>{ -20 } | ||
− | || | + | ||There are two possibilities to compute the dot product. Either the component representation <math>\vec{\mathbf{a}}\cdot\vec{\mathbf{b}} = \begin{pmatrix}a_1 \\ a_2 \\ a_3 \end{pmatrix}\cdot\begin{pmatrix}b_1 \\ b_2 \\ b_3 \end{pmatrix}=a_1b_1+a_2b_2+a_3b_3</math> is used or the angle between the vectors: <math>\vec{\mathbf{a}} \cdot \vec{\mathbf{b}} = a \vec{\mathbf{e}}_{a} \cdot \vec{\mathbf{e}}_{b} = a b \cos \alpha </math>. |
− | {''' | + | {'''Please solve the following exercise:''' |
| type="{}" } | | type="{}" } | ||
<math>\begin{pmatrix} 0 \\ 1 \\ 0 \end{pmatrix}\cdot \begin{pmatrix} 1 \\ 1 \\ 0 \end{pmatrix}=</math> { 1 } | <math>\begin{pmatrix} 0 \\ 1 \\ 0 \end{pmatrix}\cdot \begin{pmatrix} 1 \\ 1 \\ 0 \end{pmatrix}=</math> { 1 } | ||
− | || | + | ||There are two possibilities to compute the dot product. Either the component representation <math>\vec{\mathbf{a}}\cdot\vec{\mathbf{b}} = \begin{pmatrix}a_1 \\ a_2 \\ a_3 \end{pmatrix}\cdot\begin{pmatrix}b_1 \\ b_2 \\ b_3 \end{pmatrix}=a_1b_1+a_2b_2+a_3b_3</math> is used or the angle between the vectors: <math>\vec{\mathbf{a}} \cdot \vec{\mathbf{b}} = a \vec{\mathbf{e}}_{a} \cdot \vec{\mathbf{e}}_{b} = a b \cos \alpha </math>. |
</quiz> | </quiz> | ||
[[Category:Selftest]] | [[Category:Selftest]] | ||
[[Category:Vectors]] | [[Category:Vectors]] |
Latest revision as of 10:18, 25 September 2014
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