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Topic:
Prove that 2Cos(2pi/7) is a root to x^3+x^22x1.
Replies:
1
Last Post:
Sep 12, 2006 3:23 PM



Jason Fahy
Posts:
15
From:
Edmonton, AB
Registered:
9/5/06


Re: Prove that 2Cos(2pi/7) is a root to x^3+x^22x1.
Posted:
Sep 12, 2006 3:03 PM


I'm trying something involving a halfangle identity; I'll let you know if I get anywhere with it.
Edit: I got a few terms to cancel using cos^2 x = 1/2 + 1/2 cos 2x, but so far I haven't been able to finish it.
Message was edited by: Jason Fahy



