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    So in my book they wrote
    b- a
    but I wrote a- b and I was wondering if they are both considered to be the same?

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    They're the same in magnitude, but opposite in direction.
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    (Original post by Adorable98)
    So in my book they wrote
    b- a
    but I wrote a- b and I was wondering if they are both considered to be the same?

    No they are not the same because you wrote b as minus which it isn't as you travel in the direction the arrow is pointing in which means it is positive. Therefpre it can only be written as b-a or -a+b. Hope this helps!
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    (Original post by Speedbird129)
    No they are not the same because you wrote b as minus which it isn't as you travel in the direction the arrow is pointing in which means it is positive. Therefpre it can only be written as b-a or -a+b. Hope this helps!
    Okay then, so why is the answer b - a not a - b?
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    (Original post by Adorable98)
    Okay then, so why is the answer b - a not a - b?
    It is not a-b because to get from the start of the red dashed line to the end you have to travel along b in the direction the arrow is pointing, therefore b is positive. Then you travel down b in the opposite direction to the arrow, therefore it is negative. This is why b is positive and a is negative and therefore it is incorrect the other way round. Hope this helps!
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    (Original post by Speedbird129)
    It is not a-b because to get from the start of the red dashed line to the end you have to travel along b in the direction the arrow is pointing, therefore b is positive. Then you travel down b in the opposite direction to the arrow, therefore it is negative. This is why b is positive and a is negative and therefore it is incorrect the other way round. Hope this helps!
    Sorry, my mistake you travel down b and then a in the opposite direction to the arrow, therefore a is negative.
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    (Original post by Speedbird129)
    Sorry, my mistake you travel down b and then a in the opposite direction to the arrow, therefore a is negative.
    I still don't get it?
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    (Original post by Adorable98)
    I still don't get it?
    Is this for A-level?
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    (Original post by Adorable98)
    I still don't get it?
    b-a, on the diagram, is essentially moving from right to left (moving by vector b, then in the opposite direction of vector a). a-b ( a-b = -(b-a): moving by vector a, then moving in the opposite direction of vector b) is the vector moving from left to right.
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    Basically if you move in the direction that the arrow is pointing in, the letter has to be positive, therefore as you are moving through b in the direction that the arrow is pointing, b must be positive, not negative.
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    (Original post by Middriver)
    Same size different directions Attachment 539983
    Oh I see now!! Thank you!!
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    (Original post by Speedbird129)
    Basically if you move in the direction that the arrow is pointing in, the letter has to be positive, therefore as you are moving through b in the direction that the arrow is pointing, b must be positive, not negative.
    (Original post by oniisanitstoobig)
    b-a, on the diagram, is essentially moving from right to left (moving by vector b, then in the opposite direction of vector a). a-b ( a-b = -(b-a): moving by vector a, then moving in the opposite direction of vector b) is the vector moving from left to right.
    Thank you!!!
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    (Original post by Adorable98)
    Oh I see now!! Thank you!!
    No worries.
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    Thanks for the reps. Hope you understand now and is this for A-level?
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    (Original post by Speedbird129)
    Thanks for the reps. Hope you understand now and is this for A-level?
    Yep!! C4 vectors
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    (Original post by Adorable98)
    Yep!! C4 vectors
    Ok, I probably wasn't the best person to help as I am doing my GCSE's now but I would believe the basic principles are the same. Good luck in your studies and exams!
 
 
 
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