A question regarding vectors and angle between vectors

Nov 2018
1
0
In my attempt, I got 2 answers √3 and 1 but the solutions say that the answer is only √3. Am I missing something?


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ChipB

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Jun 2010
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Morristown, NJ USA
Consider the first equation you are given:

$ | \hat A \times \hat B | = - \sqrt 3 \ \hat A \cdot \hat B $

The left hand side is a positive number, since it's a magnitude. Therefore the right hand side must also be positive, which means $ \hat A \cdot \hat B$ must be negative. This rules out the possibility that theta = -60 degrees.
 
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Pmb

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Apr 2009
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Boston's North Shore
Consider the first equation you are given:

$ | \hat A \times \hat B | = - \sqrt 3 \ \hat A \cdot \hat B $
That expression is not in the paper he posted. The cross product is defined for two vectors whose magnitude does not appear explicitly in the expression defining it;.
 
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ChipB

PHF Helper
Jun 2010
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Morristown, NJ USA
That expression is not in the paper he posted.
?? It’s the very first line of the photo the OP posted from his text with the problem statement - are you not seeing it?
 
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