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Math Help - Area of triangle with vectors problem

  1. #1
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    Area of triangle with vectors problem

    P (3,0,1)
    Q (1,2,-1)
    R (2,-1,1)

    formula used 1/2 |PR x PQ|

    PR (-1,-1,-1)
    PQ (-2,2,-3)
    PRxPQ (5,-1,-4)

    so the area is 1/2 |0| = 0?
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  2. #2
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    Quote Originally Posted by thekrown View Post
    p (3,0,1)
    q (1,2,-1)
    r (2,-1,1)

    formula used 1/2 |pr x pq|

    pr (-1,-1,-1)
    pq (-2,2,-3)
    prxpq (5,-1,-4)

    so the area is 1/2 |0| = 0?
    pr =<-1,-1,0>
    pq =<-2,2,-2>
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  3. #3
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    Okay the correct cross product of pr x pq is (2,-2,-4)

    I know the formula is 1/2 |pr x pq|

    Now to calculate the area of the triangle I forget if it's the magnitude or simoply absolute value?

    If it's the magnitude then the answer should be

    1/2 | square root 24 |
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  4. #4
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    Magnitude
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