What Is the Origin of This Unexplained Formula in My Textbook?

[fahraynk]

I am seeing this formula in a textbook, unexplained. Can someone tell me the origin, the book just says it is an identity.

$$Re(Ee^{jwt})=\frac{1}{2}(Ee^{jwt}+E^*e^{-jwt})$$
The book doesn't explain what $E^*$ is, it just lists the formula. Re = real, as in take the real part. E is the electric field, but I guess it could also be any dummy variable.

Does this formula have a name, so that I can figure out what $E^*$ is?

 

[fresh_42]

$E^*$ is the complex conjugate. The formula is simply $Re(z+\bar{z}) = 2Re(z)$.