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Homework Help: Linear Algebra - How to get matrix form Ax.

  1. Feb 22, 2012 #1
    1. The problem statement, all variables and given/known data
    I know the title is misleading but what I am asking is how I can get this matrix

    to the matrix multiplication form
    cosθ -sinθ | x1
    sinθ cosθ | x2

    cosθ -sinθ
    sinθ cosθ

    Is there a good method to do this or do I have to find it by eye-balling it?
  2. jcsd
  3. Feb 22, 2012 #2


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    Science Advisor

    have you tried perfoming the matrix multiplication:

    [tex]\begin{bmatrix}\cos\theta&-\sin\theta\\ \sin\theta&\cos\theta\end{bmatrix}\begin{bmatrix}x_1\\x_2\end{bmatrix} = ?[/tex]

    and comparing that to what you want?
  4. Feb 22, 2012 #3


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    Staff Emeritus
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    Homework Helper
    Education Advisor

    What's the usual way of finding the columns of the matrix representing a linear transformation? It should be mentioned in your book somewhere.
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