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Vector Problem - is this even solvable?

by The_Chromer
Tags: algebra, physics, vector
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The_Chromer
#1
Sep10-11, 12:45 AM
P: 15
1. The problem statement, all variables and given/known data



2. Relevant equations
I'm considering cross product and dot product rules, yet I don't know where to begin with this one.


3. The attempt at a solution
I have two pages of scratch paper that is littered with failed attempts to solve the problem.

-There are no values for a or b given.
-Is there even enough information to solve these problems?
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wukunlin
#2
Sep10-11, 12:57 AM
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this is basically a set of 2X2 simultaneous equation, which you can do by seperating the two components of each vector
SteamKing
#3
Sep10-11, 01:02 AM
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Thanks
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Hint: a and b are constants which multiply the vectors A and B, respectively. There is no implied dot or cross product in the problem statement as shown.

The_Chromer
#4
Sep10-11, 01:18 AM
P: 15
Vector Problem - is this even solvable?

I think I'm on the right track... thanks guys. Can you confirm if this is heading in the correct direction?

a<81,-73>+b<-79,49>+<60,85>=<0,0>

So,

81a-79b+60=0
-73a+49b+85=0

?
wukunlin
#5
Sep10-11, 01:19 AM
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yup :)
The_Chromer
#6
Sep10-11, 01:21 AM
P: 15
These numbers are ugly... mind sticking around until I work it out? :)
The_Chromer
#7
Sep10-11, 01:30 AM
P: 15
Still haven't figured it out :/
wukunlin
#8
Sep10-11, 02:02 AM
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do you have to solve it by hand? or are you allowed to use calculators/computers?
The_Chromer
#9
Sep10-11, 02:03 AM
P: 15
Even if I solve it, I still think there's something going wrong... I'll use a computer. I just tried doing it with matrices, lol.
wukunlin
#10
Sep10-11, 02:06 AM
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you can always substitute your answers back into the question and see if the identity holds, faster and simpler than rechecking all your steps
The_Chromer
#11
Sep10-11, 02:10 AM
P: 15
You're right - I have new values for a and b

a=5.520297
b=6.489422

Pretty sure I got it! Thank you for your help!
wukunlin
#12
Sep10-11, 02:11 AM
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glad to help :)
The_Chromer
#13
Sep10-11, 02:12 AM
P: 15
It was correct - my online homework thing accepted it, lol. The algebra was just a little ambiguous.


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