By considering from k=0 to k=n-1, show that

stuck here

please help

and i also dont know how to put limits in summation :P please tell that too

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- April 24th 2013, 02:11 AMmathfag188de moivre theorem and summation
By considering from k=0 to k=n-1, show that

stuck here

please help

and i also dont know how to put limits in summation :P please tell that too - April 24th 2013, 03:25 AMBobPRe: de moivre theorem and summation
Start by writing as

and then make use of De Moivre's theorem. - April 24th 2013, 07:01 AMmathfag188Re: de moivre theorem and summation
i already did what you told but cant go any further

can you please continue after that? - April 24th 2013, 08:19 AMBobPRe: de moivre theorem and summation
If you do as suggested the summation can be split into two parts, one real the other imaginary.

The summation itself can be summed easily since it is a GP with common ratio

Do that and then equate reals and imaginaries across the two results.

(Actually, you only need to equate reals.)