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Homework Help: Vectors problem trouble

  1. Jan 19, 2010 #1
    The two vectors a and b have equal magnitudes of 13.0 m and their angles are θ1 = 30° and θ2 = 100°.
    Find the components of their vector sum, r.

    I know this is a very simple problem, but I can't get it! And it is frustrating me to no end.

    I know the y component of the sum is 16.3. (I don't remember how I got this, but it's right.)
    However, when I try to find the x components of each vector, I get 11.26 for a, and -2.26 for b. When these are added, you get 9.0. And the computer(our HW is graded online) is telling me that this is the wrong answer.

    What am I doing wrong?!
  2. jcsd
  3. Jan 19, 2010 #2


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    Hi STEF2098! :smile:

    hmm … I make it 9.0 also, but I don't get 16.3 :confused:

    are you sure it's not |a| = |b| = 11.0 m?
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