why cos(pi)=-1 e cos(-pi)=-1 ???
I think this is
(-1)^[ cos(-pi) ]
Note that we have a trig identity that says cos(theta) = cos(-theta)
So.... cos (pi) = cos(-pi) = -1
So
(-1)^[cos(-pi)] =
(-1)^{ -1 ] =
1 / - 1 =
-1
