What are cos(n*π - π) and cos(n*π + π) n is integer, always equals to

I know that cos(n*π) = (-1)^n

but what about these two?

Siπ=0
Cosπ=1
Cos(nπ-π)=Cosnπ Cosπ+Sinnπ Sinπ=Cosnπ=-(-1)^n for n>=0

Cos(nπ+π)=Cosnπ Cosπ-Sinnπ Sinπ=Cosnπ=-(-1)^n for n>=0

Cosnπ=-(-1)^n

All of those graphs are effectively the same. You're not exactly clear on what you're asking for.