I apologize if my response seemed argumentative. It wasn't intended that
way. Certainly, sin^2(wt) has the same shape as the power waveform I
derived -- the only difference is its fixed D.C. term. And I certainly
agree that letting delta t approaching zero doesn't make any function of
t become zero at that point. And just as the analysis I've presented is
in your first year college electronics book, so is the point about delta
t in everyone's high school or first semester college calculus book. But
it's evident that some number of participants in this thread have either
forgotten, never seen, or never understood those basic principles. And
quite a few people either don't have any textbooks, don't understand
them, or are unwilling to open and read them. Hence the postings
containing information that you or I could find in moments.

Roy Lewallen, W7EL

Cecil seemed to indicate that he thought delta t going to zero meant that
t was perpetually zero. I know he knows better than that.
73,
Tom Donaly, KA6RUH