
#1
Oct2110, 06:38 PM

P: 187

1. The problem statement, all variables and given/known data
Find two vectors, v1, and v2, whose sum is <4,1,1>, where v1 is parallel to <2,5,4>, and where v2 is perpendicular to <2,5,4> 2. Relevant equations I am guessing I use the cross product for this equation, but I'm confused about how to start this problem. 3. The attempt at a solution any hlep at all would be greatly appreciated! 



#2
Oct2110, 06:49 PM

Mentor
P: 21,069

Write v1 and v2 using coordinates. You're given that they add to <4, 1, 1>. You're also given that v1 is parallel to <2, 5, 4>, which means that v1 is some constant multiple of <2, 5, 4>. You're also given that v2 is perpendicular to <2, 5, 4>. Two vectors being perpendicular should suggest a particular operation. 



#3
Oct2110, 06:55 PM

P: 187

So, first I realized that v1= K<2,5,4>
Then I figured that since v1+v2=sum, ; then: <4,1,1>  K<2,5,4> = v2 Now, what process would I use to find K? 



#4
Oct2110, 07:26 PM

Mentor
P: 21,069

Simple Vector ProblemAlso what can you do with the given information that v2 is perpendicular to <2, 5, 4>? 


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