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Math Help - Vectors and Magnitudes

  1. #1
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    Vectors and Magnitudes

    Find the component form of a vector v given the magnitude of u and u+v and the angles that u and u+v make with the positive x-axis.

    sorry, fixed.....
    ||u||=2, \theta = 230, ||u+v|| = 8 \theta = 80


    I can't find any problem like this in the book, instructor gave us this as a take home problem to work on....

    Last edited by 92stealth; February 15th 2009 at 12:51 PM.
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  2. #2
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    red x bro.. can't see anything..
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    Quote Originally Posted by 92stealth View Post
    Find the component form of a vector v given the magnitude of u and u+v and the angles that u and u+v make with the positive x-axis.
    If you have the magnitude of \textbf u and \textbf u+\textbf v, along with their angles, it should be easy to get their component forms. Once you have that, \textbf v is simply \textbf (\textbf u+\textbf v)-\textbf u\text.

    You could also set it up as a triangle with sides of length \lVert\textbf u\rVert, \lVert\textbf v\rVert, and \lVert\textbf u+\textbf v\rVert, and angle |\theta_1-\theta_0|. You can use the law of cosines to get \lVert\textbf v\rVert\text.

    Edit: Now that you have posted the actual values, I see that your problem is much simpler. \textbf u and \textbf u+\textbf v, make the same angle with the x-axis, which means that they are parallel. What does that tell you about \textbf v?
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  4. #4
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    wow, i am 100% not on my game today. I messed up that first post once again, should have been 80 degrees on the second -.- sorry
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