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Math Help - find angle between vectors .. confusion.

  1. #1
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    find angle between vectors .. confusion.

    u * v / |u| |v| = cos theta

    how is -14/39 = cos theta = 1.94?

    if -14/(13 * 3) = cos theta

    please help if this makes any sense.

    find the angle between u and v give your answer to the nearest .01 radians.
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  2. #2
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    Quote Originally Posted by rcmango View Post
    ...

    if -14/(13 * 3) = cos theta

    ...

    Hello,

    you have: cos(θ) = -14/39. Now use the arccos-function:

    arccos(-14/39) = 1.9379651...

    EB
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  3. #3
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by rcmango View Post
    -14/39 = cos theta = 1.94
    Pet Peeve alert!

    Are you seriously suggesting that -14/39 = 1.94 ?? Be careful of what you write. Students have lost points on tests for less!

    -Dan
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