# How is sin(npi/2) = (-1)^((n-1)/2) for odd n?

1. Sep 19, 2009

### jaejoon89

I know the MacLaurin series for sin(x) but can't figure out how this reduces to the above (if it does).

2. Sep 19, 2009

### JG89

sin(npi/2) is going to be equal to -1 or 1, depending on the value of n, right? So the formula seems plausible. You could prove it through induction.

Last edited: Sep 19, 2009
3. Sep 19, 2009

thanks