i know it's supposed to be a simple question. frustrating because it is not coming to me. just want a hint.(adsbygoogle = window.adsbygoogle || []).push({});

question is:

how do you write

1 + cos(theta) + cos (2*theta) + cos(3*theta).... cos(n*theta) using the fact that (z^(n+1) -1) / (z^(n) -1) = 1 + z + z^(2) +... + z^(n)

thanks in advance

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# Complex analysis question (only need a hint)

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