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Math Help - Vector multiplication Very urgent: 15 mins

  1. #1
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    Vector multiplication Very urgent: 15 mins

    Hi. i really need help quick. Im doing a question where I have to find the tangent of a function.

    I have 2 vectors r_u and r_v.

     r_u = i + 2uk \ \text{and} \ r_v = j +2vk

    I just need to find the normal vector at the point (1,-1,2) which is given by  r_u * r_v but its been so long since ive done this i forgot how to multiply these two.

    I have a matrix

    i j k
    1 0 2u
    0 1 2v


    after this i have no problem finding the tangent. Please help
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  2. #2
    Moo
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    Hello,

    Have a look here : Cross product - Wikipedia, the free encyclopedia

    The formula is given :

    \begin{array}{ccc} i & j & k \\ a_1 & a_2 & a_3 \\ b_1 & b_2 & b_3 \end{array}

    The cross product is the determinant of this matrix. Use Sarrus's rule Rule of Sarrus - Wikipedia, the free encyclopedia
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