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Homework Help: Another vector problem

  1. Jan 29, 2010 #1
    Two vectors are given by avector = 3.5i + 4.5j and bvector = 2.0i + 5.0j. Find the following:

    (a) avector x bvector

    (b) avector ·bvector

    (c) (avector + bvector ) · bvector

    (d) the component of avector along the direction of bvector
    these are the answers i got

    b) 29.5
    c) 58.5

    i know that a through c are correct but d is incorrect, i calculated d by

    cos-1 (29.5/(5.7*5.39) = 16.2

    the 5.7 came from sqrt(3.5²+4.5²)
    5.39 came from sqrt(2²+5²)

    thanks in advance
  2. jcsd
  3. Jan 29, 2010 #2


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    Homework Helper

    OK, so the angle between the vectors is 16 degrees. What did you do to calculate the projection of A on B?
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