Even & Odd Signals
An even signal has the following property:
$ x(t)=x(-t) $
An odd signal has the following property:
$ x(t)=-x(-t) $
Every signal can be written as a sum of even and odd parts, i.e.:
$ x(t)=x_{E}(t)+x_{O}(t) $
where
$ x_{E}(t)=\frac{x(t)+x(-t)}{2} $
$ x_{O}(t)=\frac{x(t)-x(-t)}{2} $