Hello, Could someone please Help with proving the Complex variable equation

(a) If $\displaystyle e^z$ E R. show that Im $\displaystyle z = n \pi$. where n E Z

and if [TEX]e^z E i . R. then what is z =?

Also, if someone knows of any book online or a resource that would help me with Basic Trancendental Functions chapter in complex variables, it will be GREATLY appreciated. The book that we have is completely useless