Question

HoW tO dO tHiS ?!
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Answer 1

If none of us can help you show that this equation is true, then AoPS may help you: http://www.artofproblemsolving.com/Forum/viewforum.php?f=150

Answer 2

^_^

Answer 3

choose a cubic equation whose roots are \(\large \cos \frac{2\pi}{7}, \cos \frac{4\pi}{7}, \cos \frac{8\pi}{7}
\)

Answer 4

\[\large x^3-(\frac{-1}{2})x^2 + (\frac{-1}{2})x - (\frac{1}{8}) = 0\]

Answer 5

hmmm ,idk im not sure if i understand it