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Old April 6th, 2007, 12:49 PM
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Default Products of the unit circle

Here is the problem:
Let P sub 0, ....., P sub n-1 be n equally spaced points on the unit circle. Compute the product of the distances from P sub 0 (naught) to all the remaining points.
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Old April 6th, 2007, 01:31 PM
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Quote:
Originally Posted by chadlyter View Post
Here is the problem:
Let P sub 0, ....., P sub n-1 be n equally spaced points on the unit circle. Compute the product of the distances from P sub 0 (naught) to all the remaining points.
I do not understand. What distances and what products.

First we know that,
P_k = exp((2pi/n)*ki)

Now what?
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Old April 6th, 2007, 01:42 PM
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This is my understanding.
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Old April 6th, 2007, 03:35 PM
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Originally Posted by Plato View Post
This is my understanding.
In that case the product is equal to "n" itself.
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Old April 6th, 2007, 04:43 PM
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In that case the product is equal to "n" itself.
Correct! What is the proof?
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Old April 8th, 2007, 09:51 AM
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Originally Posted by Plato View Post
Correct! What is the proof?
Not an easy question to answer.
But we can begin by simplifing.
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Old April 8th, 2007, 10:53 AM
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I am going in unit circles (get the pun) with this problem.

But I managed to make this problem more complicated than it should be. Instead of working with cyclotonomic polynomials, as I should have. I reduced the problem to trigonometry which makes it more difficult.


I am sure you know what I am about to say but let me just post it.

A cyclotonomic polynomial is,
\Phi_n(z) = 1+z+z^2+...+z^n

We can factor them as,
(z-z_1)(z-z_2)+...+(z-_n)
Where,
z_1,z_2,...,z_n
Are points on the regular (n+1)-gon inscribed in the unit circle in the complex plane (except unity).

Basically, I am saying this is the cyclotonomic polynomial of degree n evaluated at 1.
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Last edited by ThePerfectHacker; April 8th, 2007 at 11:23 AM.
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