# SImple Vector Problem Help (1 Viewer)

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#### Loppyfoot

1. The problem statement, all variables and given/known data

Consider the line L(t) =<2-t,1+4t,4+2t> and the point P =(5,0,-4).
How far is P from the line L?
2. Relevant equations

3. The attempt at a solution
I'm confused on how to being this problem.

Any ideas would be great!

#### irycio

Not a very geometric approach to this problem, but nevertheless gave a correct result, or at least the one that looks fine when plotted.

Anyway, find all the vectors connecting point P to the line L, all of them being a function of t (your parameter). This is pretty simple. Now, calculate the length of such vectors. Actually, length squared will do as well. This again is a function of t, isn't it? Now, what you want to find is the shorthest from all those vectors. So what do you do? Yep, you are looking for a minimum of the latter function. Once you find the value of the parameter, for which a vector LP is the shortest, you are at home :)

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