cos(n*x) when n is natural and x=pi equals to (-1)^n as I wrote in the pic.
What I'm looking for is the same thing in sinus, lets say again that n is natural, is there a x that can make sinus to behave something like cos? and by that I mean an expression that can be written in on line like (-1)^n (x can be anything).
I hope that was understood.
Thanks in advance.