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Anonymous
Anonymous asked in Science & MathematicsMathematics · 9 years ago

Calculus question about vectors!?

If a dot b = squareRoot(3) and a cross b = <1,2,2>, find the angle between a

and b.

The answer is 60 degrees but the question is HOW?? i dont understand and how to compute this. please help.

2 Answers

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  • dennis
    Lv 6
    9 years ago
    Favorite Answer

    a . b = |a| |b| cos x = √3

    | axb| = |a| |b| sin x = |(1,2,2)| =3

    so tan x = √3 so x = 60.

  • Anonymous
    9 years ago

    |a||b|cos(t) = sqrt(3)

    |a||b|sin(t) = |<1,2,2>|=3

    --->|a||b|= 2sqrt(3) ---> cos(t)=1/2 ---> t = 60degs

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