Anonymous
Anonymous asked in Science & MathematicsMathematics · 1 month ago

Find u × v, v × u, and v × v. u = (9, 2, 1)  v = (−4, 8, −2 )?

3 Answers

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  • Pope
    Lv 7
    1 month ago

    You have been given correct answers for the first two. As for v × v, the cross product of any 3-dimensional vector with itself returns the zero vector.

    |v × v| = |v| |v| sin(θ)

    The angle θ is the angle between the two argument vectors. Since the vectors are identical, the angle between them is zero, and sin(0) = 0.

  • 1 month ago

    First note that u x v = - v x u so you only have to do the multiplications once.

    u x v = i*(-4 - 8) + j*(-4 - (-18)) + k*(72 - (-8))

          = i*(-12) + j*14 + k*80 =(-12, 14,80)

    v x u = - u x v = (12, -14, -80)

  • rotchm
    Lv 7
    1 month ago

    Just plug in your given values and do the cross multiplication. 

    You do know the procedure, right? It's just following the procedure, following the rules. 

    If you were not anon I would detail further.

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