Looks like a phasor diagram to me.
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Many years ago, when Marconi was a boy, there were vector diagrams which could be considered either as an X-Y plot or a polar coordinate plot of some electrical quantity.
Then someone decided that boring old vector diagrams were just not the thing to have anymore, we would have phasor diagrams, just the same as a vector diagram but change the name to confuse the students.
It looks like we now have sinor diagrams, maybe so that people do not confuse them with a futuristic beam energy weapon from a popular science fiction series (Beam me up Scotty).
cynical_mode off/
JimB