// Numbas version: exam_results_page_options {"name": "Vectors: when perpendicular 1", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"functions": {}, "ungrouped_variables": ["a", "c", "b", "d", "g", "f", "s3", "s2", "s1", "s5", "s4"], "name": "Vectors: when perpendicular 1", "tags": ["dot product", "finding perpendicular vectors", "inner product", "perpendicular vectors", "product", "scalar product", "vectors"], "preamble": {"css": "", "js": ""}, "advice": "
$\\boldsymbol{A}$ and $\\boldsymbol{B}$ are perpendicular to one another when $\\boldsymbol{A \\cdot B} = 0$.
\nNow \\[ \\begin{eqnarray*}\\boldsymbol{A \\cdot B} &=& \\simplify[]{{a}*{c}+{b}*{d}+lambda*{f}}\\\\ &=& \\simplify[std]{{f}*lambda+{a*c+b*d}} \\end{eqnarray*} \\]
Hence \\[\\boldsymbol{A \\cdot B} = 0 \\Rightarrow \\simplify[std]{{f}*lambda+{a*c+b*d}=0} \\Rightarrow \\lambda = \\simplify[std]{{-a*c-b*d}/{f}}\\]
$\\boldsymbol{A}$ is in the $xy$ plane when $\\lambda=0$.
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\n$\\lambda =\\;\\;$ [[0]].
\nEnter your answer as a fraction or an integer and not as a decimal.
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\n$\\lambda =\\;\\;$ [[0]].
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\\[\\boldsymbol{A}=\\simplify[std]{{a}v:e_1+{b}v:e_2+lambda*v:e_3},\\;\\;\\;\\boldsymbol{B}=\\simplify[std]{{c}v:e_1+{d}v:e_2+{f}v:e_3}\\]
15/07/2012:
\n \t\tAdded tags.
\n \t\tLast part is too easy.
\n \t\t16/07/2012:
\n \t\tAdded tags.
\n \t\tQuestion appears to be working correctly.
Agree that last part is too easy.
When are vectors $\\boldsymbol{A,\\;B}$ perpendicular?
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