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Math Help - Linear combinations

  1. #1
    Member wiseguy's Avatar
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    Linear combinations

    The graph of y = cos (x - 1.3) is a sinusoid with a phase displacement of 1.3 radians.
    Given that cos 1.3 ≈ 0.27 and sin 1.3 ≈ 0.96, write y as a linear combination of cos x and sin x.

    My responce:

    y=cosxcos1.3+sinxsin1.3

    I'm new to linear equations so I want to make sure I'm doing this correctly...
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  2. #2
    Super Member Failure's Avatar
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    Quote Originally Posted by wiseguy View Post
    The graph of y = cos (x - 1.3) is a sinusoid with a phase displacement of 1.3 radians.
    Given that cos 1.3 ≈ 0.27 and sin 1.3 ≈ 0.96, write y as a linear combination of cos x and sin x.

    My responce:

    y=cosxcos1.3+sinxsin1.3

    I'm new to linear equations so I want to make sure I'm doing this correctly...
    Looks ok to me. However, you haven't made use of the given values of of cos and sin for the argument 1.3. So the expected answer seems to be:

    y\approx 0.27\cos x+0.96\sin x
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