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Homework Help: Vectors: The Dot Product

  1. May 1, 2007 #1
    Need help with this problem. I need to show that one side equals the other. I this is distributive property but isnt that just too plain simple? I mean im in pre-cal class and therefore this question cant be easy as it seems.... ::biggrin:

    anyways, if anyone knows about vector plez help me with this.

    b2f05b38c36ddff421b6f2f85f6275a7.png
     
    Last edited by a moderator: Apr 22, 2017
  2. jcsd
  3. May 1, 2007 #2

    robphy

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    Realize that the plus-symbol on the left applies to adding vectors,
    whereas the plus-symbol on the right applies to adding scalars.

    What is your working definition of the dot-product?
    ab cos(angle between)? or ax*bx+ay*by+az*bz? or something else?
     
  4. May 1, 2007 #3
    Hi,

    Thanks for quick reply.
    the teacher provide the following definition for the dot product:

    The dot product of U = (U1, U2) and V = (V1, V2) is
    U * V = U1V1 + U2V2
     
  5. May 1, 2007 #4
    So, state the forms of each vector involved in terms of their components, then perform the scalar multiplications longhand. The definitions should drop right out.
     
  6. Aug 4, 2007 #5
    i have a text book that states; teh dot product of x1,x2 and y1,y2 is x1y1 - x2y1 -x1y2 + 4x2y2

    how can that be? the it states the dot product of x1,x2 and x1,x2 is (x1-x2)^2 +3Xx^2 ? plz help
     
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