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Thread: Find so that these vectors are mutually perpendicular

  1. #1
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    Find so that these vectors are mutually perpendicular

    Find c so that these vectors are mutually perpendicular:
    a = <c,−2, 3> and b = <c, c,−5>.

    how would you go about doing this.

    I know how to apply the cross product.
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  2. #2
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    Two vectors are perpendicular if their dot product is $\displaystyle \displaystyle 0$.
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    thanks for response and yes i agree if its 0 its mutually perpendicular.

    would i have to put a = <c,−2, 3> and b = <c, c,−5> into its determinant form then solve?
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    No, take the dot product and set it equal to $\displaystyle \displaystyle 0$. Then solve the resulting quadratic.
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    ok i see

    i got an answer of −3 or it could be 5 i think that's correct
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  6. #6
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    Yes that is correct.
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