# What is result of this summation:sum(k=1, to n) sin(n*pi/k)I

1. Apr 15, 2012

### Emilijo

What is result of this summation:

sum(k=1, to n) sin(n*pi/k)

I put it in wolfram alpha but it doesn't give me the solution.
Where is the problem?

2. Apr 15, 2012

### tiny-tim

try using sinθ = Im(e)

3. Apr 15, 2012

### Emilijo

Re: summation

No, still doesn't calculate it.

4. Jun 12, 2012

### rbj

Re: summation

first of all, are you sure it isn't

$$\sum_{k=1}^n \sin(k \pi / n)$$

instead?

second, in any case, complex numbers and variables, Euler's formula, and the sum of a geometric series are three mathematical methods that are your friends.

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