There are planning processes to use, but in "real life" you'll draw on knowledge from across all areas because you need to consider stakeholders, communication, scheduling, risk etc etc as you work out how the project will progress.
I have a question for you, when planning the details of your project does the PM use just one of the knowledge area or does the PM use certain processes from all 12 know areas to build a project? I would assume the PM would use processes from all Knowledge Areas.
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