Re: Help find min poly.

From: James Buddenhagen (foo_bar_at_texas.net)
Date: 02/14/05 

Date: Mon, 14 Feb 2005 15:14:29 GMT

"Steve" <carvegio@gmail.com> wrote in message
news:200502141132.j1EBW3032255@proapp.mathforum.org...
> Hey I am trying to figure out how we would find the minimal
> polynomial of 2*cos(2*pi/7).
>
> Anyone have any ideas or a method for this?
>
> thanks

A related problem: show that if a=2*cos(2*Pi/7), b=2*cos(4*Pi/7),
and c=2*cos(6*Pi/7), then -(a+b+c)=1, a*b+b*c+c*a=-2, and -a*b*c=-1.

This then suggests a cubic polynomial with roots a,b,c.

Jim Buddenhagen