Vector Multiplication

  • Thread starter markyp23
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  • #1
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Homework Statement



"PRQSTU is a regular hexagon of side 2 units. PQ,QR and RS represent vectors a, b andc respectively. Find the value of a.(b + c)

The hexagon is a regular hexagon starting at the far left (ie pointing left) with P then anti clockwise through U at the top left.

Homework Equations



None that I can think of.

The Attempt at a Solution



I really don't know where to start. I've guessed that a (PQ) = -c. But I don't know where to go from there and now I'm really confused.

Any help greatly appreciated.
 

Answers and Replies

  • #2
Dick
Science Advisor
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You must be drawing a pretty horrid picture of a hexagon to be guessing that a=(-c). If you draw a neat picture you will probably realize there is a special angular relationship between a and b+c. You could also just tough it out and compute the components of the vectors a, b and c, since you know their lengths and the angles between them.
 
  • #3
9
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Thanks for the reply.

I think I realised why I was lost - it's because I was! We haven't been taught this part of vectors yet, and I was looking at a past paper.

Haha, oops. The picture was already printed for me and I thought that a=(-c). I better stick to diagrams of squares. :)
 

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