Daisy R.

asked • 04/04/14

Can someone help me with this questions?.But please dont give me the answer.I just dont understand this lesson

1)Find the cross product and show it is orthogonal to both u and v.
u=<-3,2,3>
v=<0,1,0>
 
2)Find the cross product and show it is orthogonal to both u and v.
     u=6k
     v=-i+3j+k
 
 
3)Find the area of the parrallelogram that has the two vectors as adjacent sides
 
u=2i+4j+6k
v=i+k
 
4)Find the cross product of the unit vectors
                   J×k
                 i j k
                0 1 0
                0 0 1
 
 
THE LESSON IS CROSS PRODUCT OF TWO VECTORS

1 Expert Answer

By:

Daisy R.

So i have to multiply u and v
?
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04/04/14

Jim S.

tutor
u cross v  is the definition of the vector cross product you calculate the components by multiplying the components of u and v together as I've shown above.
Would you like me to work the whole problem for you completely?
jim
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04/04/14

Daisy R.

:( ok thank you
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04/04/14

Jim S.

tutor
Daisy,
              you were given u an v as components u=<-3,2,3>
v=<0,1,0> 
 
so u=-3i+2j+3k and v=j
 
and u x v= (uyvz-uzvy)i + (uzvx-uxvz)j + (uxvy-uyvx)k =(2*0-3*1)i+(3*0-(-3)*(0))j + (-3*1-2*0)K=-3i+0j-3K=u cross v and this vector is perpendicular to v because (-3i-3k)•j=0 because i and k are perpendicular to j so i•j=0 and k•j=0.
Hope this helps a little
Jim
 
 
 
 
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04/05/14

Jim S.

tutor
Daisy,
          Try this link for additional help with the cross product.
Jim
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04/05/14

Daisy R.

What link?
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04/06/14

Jim S.

tutor
Sorry, Here's the link.
 
http://onlinemschool.com/math/assistance/vector/multiply1/
 
Jim
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04/06/14

Daisy R.

Can you tell my if my answers are wron? 
 
For number 4. I found the cross product to be 1i-0j+0k
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04/06/14

Jim S.

tutor
Yes you are correct jxk=i You got it now nice work
Jim
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04/06/14

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