# Scalar product of position vectors

#### nokia8650

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#### CompuChip

Homework Helper
Suppose, in general, that you have a function f(t). How do you find its minimum and maximum (i.e. the extrema)?

[Hint: it involves differentiation]

#### nokia8650

find values of t for f'(t) =0

I dont understand the significance of r.r, however.

Thanks

#### CompuChip

Homework Helper
Well, r is the vector that describes the difference in position.
r . r is the square of its length. So the square of the distance between the particles.

Note that minimizing (maximizing) the distance is equivalent to minimizing (maximizing) the square of the distance.

"Scalar product of position vectors"

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