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9.4 - Reading questions
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<h2>[9.4] - Reading Assignment
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<p class="show"><b>Read</b> section 9.4 in the textbook.
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<li>Why is it that if $\myv a \cdot (\myv b \times \myv c)=0$ then 
$\myv a$, 
$\myv b$, and $\myv c$ are coplanar?<br>
<p class="justme answer"> The vector $\myv n=\myv b \times \myv c$ is certainly perpendicular to $\myv b$ and $\myv c$.  If ($\myv a \times \myv b)\cdot \myv c=0$ that means $\myv n$ is perpendicular  to $\myv c$ as well.  So all three vectors are perpendicular to $\myv n$.  And we define a plane as all the vectors which are perpendicular to a particular normal vector $\myv n$.  So they're all in the same plane.
<li>What is the volume of the parallelepiped defined by the vectors
$\myc{1,1,1}$, $\myc{0,1,1}$, and $\myc{1,2,0}$?

<p class="justme result"><img src="../gco/0g/9.3.2.png"><br>
<p class="justme answer">Answer: 2.  So show your calculations...</p>
<li>What other questions / musings / muddy points from the reading?


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