The symbiotic relationship between EA and IT governance can be expressed in functions of input producing output from one to the other. Please note that I present the following as one example of that idea not a comprehensive picture of the yin and yang of the two overlapping disciplines.
IT governance outputs include reporting structure, roles, and responsibilities within the IT function whether there is an IT department or not. So in that sense, the output from IT governance is the establishment of an EA role or position within the corporate hierarchy.
On the other end of the relationship, EA produces models of the business processes, both “as-is” and “to-be”, within the context of governing structures. EA output could result in a “to-be” model requiring changes to the IT governance structure or process in order to realize added value.