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Math Help - Vector question 2

  1. #1
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    Vector question 2

    Use cross product to find the sine of the angle between the vectors

    u (2,3,-6)
    v(2,3,6)
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  2. #2
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    Quote Originally Posted by daphnewoon View Post
    Use cross product to find the sine of the angle between the vectors

    u (2,3,-6)
    v(2,3,6)
    Use the definition of the cross product:

    |\vec u \times \vec v|= |\vec u| \cdot |\vec v| \cdot \sin(\vec u, \vec v)

    Solve for \sin(\vec u, \vec v)
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  3. #3
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    Hello, thanks for replying
    I know the formula to solve this question, just that i've gt this equation:

    (36 , -30, 0) = 10 sin alpha

    How am i going to manipulate this?
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  4. #4
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    Quote Originally Posted by daphnewoon View Post
    Hello, thanks for replying
    I know the formula to solve this question, just that i've gt this equation:

    (36 , -30, 0) = 10 sin alpha

    How am i going to manipulate this?
    I'm not sure how you got this result ...

    Use the formula I posted in my previous answer:

    <br />
|\vec u \times \vec v|= |\vec u| \cdot |\vec v| \cdot \sin(\vec u, \vec v)<br />
    Plug in all the values you know:

    |(2,3,-6) \times (2,3,6)|= |(2,3,-6)| \cdot |(2,3,6)| \cdot \sin(\vec u, \vec v)

    |(36, -24, 0)|= 7 \cdot 7 \cdot \sin(\vec u, \vec v)

    12 \cdot \sqrt{13}= 49 \cdot \sin(\vec u, \vec v)

    ... and now solve for \sin(\vec u, \vec v)
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