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calculate the distance from a point to a line in R3 watch

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    Calculate the distance from P(1,1,1) and L: (0,-5/3,-8/3) + (lambda)(1,1,3)

    Ended up with 1/33 sqrt(29^2 +(-26)^2 +(-1)^2). Have ended up with a very weird number!
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    I think you've made an arithmetic mistake somewhere. Also, if I'm not mistaken, the numbers have been chosen so it comes out reasonably nicely.

    I suggest you post your working.
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    Bit too slow:

    I suspect a sign error - did the same thing myself first time.

    I get \sqrt{2}, now.
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    (Original post by ghostwalker)
    Bit too slow:

    I suspect a sign error - did the same thing myself first time.

    I get \sqrt{2}, now.
    Where was your sign error?
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    (Original post by Lunu)
    Where was your sign error?
    Subtracting a negative dot product.

    As DFranklin suggested, post your working.
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    (Original post by ghostwalker)
    Subtracting a negative dot product.

    As DFranklin suggested, post your working.
    I hope this attaches
    Attached Images
     
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    (Original post by Lunu)
    I hope this attaches
    You've taken the dot product of a with p, rather than with b.
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    (Original post by ghostwalker)
    You've taken the dot product of a with p, rather than with b.
    So which two vectors should I use? Very confused!
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    (Original post by Lunu)
    So which two vectors should I use? Very confused!
    PX, which is "b" in your working - the vector from the point P to a point on the line - and
    "a" in your working - the direction vector for the line.

    Edit: You worked out b, but then didn't use it.
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    (Original post by ghostwalker)
    PX, which is "b" in your working - the vector from the point P to a point on the line - and
    "a" in your working - the direction vector for the line.

    Edit: You worked out b, but then didn't use it.
    Thank you!
 
 
 
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Updated: October 17, 2015
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