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avatar+84 

Find the area of the parallelogram that has the vectors as adjacent sides

u=-2i+j+5k

v=4i-3j-3k

 

a. 11

b. sqr rt 26

c. 86

d. 2  sqr rt 86

e. 1

 Aug 29, 2016
 #1
avatar+128731 
0

u=-2i+j+5k

v=4i-3j-3k

 

The area   =    ll  u x v ll

 

u x v  =   det   [  i   j   k 

                         2  1  5

                         4  -3 -3 ]      write the first two columns again and take the det

 

[  i    j    k     i    j

  2   1    5    2  1

  4   -3  -3    4  -3 ]    

 

[  -3i + 20j  -6k ] - [ 4k -15i - 6j ] = 

 

[12i + 26j - 10k ]

 

And the area =  sqrt [ 12^2 + 26^2 + ( -10)^2]  = sqrt (920)  = sqrt (4 * 230) =  2sqrt (230)

 

 

cool cool cool

 Aug 29, 2016
 #2
avatar+84 
0

Thank you! Could you help me to figure out which of the answer options this is, as I don't have your answer as as one of the options?!

 Aug 30, 2016
 #3
avatar+33616 
+1

CPhill has written 2 instead of -2 in the matrix. If you correct this and then repeat his process you should come up with one of the specified answers.

Alan  Aug 30, 2016

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