Thread: is this true?
View Single Post
  #3  
Old November 6th, 2009, 11:39 AM
Drexel28's Avatar
Drexel28 Drexel28 is offline
MHF Contributor
  
Join Date: Nov 2009
Location: Philadelphia, PA
Posts: 1,899
Country:
Thanks: 74
Thanked 560 Times in 522 Posts
Drexel28 is a name known to allDrexel28 is a name known to allDrexel28 is a name known to allDrexel28 is a name known to allDrexel28 is a name known to allDrexel28 is a name known to all
Default
Of course assuming that n\in\mathbb{N}. Otherwise, not so much. If you don't make that restriction you need to say that \cos(n\pi)=\mathfrak{R}\left((-1)^n\right) which is really just a highfalutin way to say \cos(n\pi). This is of course because (-1)^n=e^{\pi\cdot i\cdot n}=\cos(n\pi)+ i\sin(n\pi).
Reply With Quote