In Response To 'Re: Re: Re: making a transformation'
Thanks for your help on this.
I understand what you are saying, but if you'll notice in my .nb attachment all the examples that worked were exactly the same as the ones that didn't work. Only the font was different.That's what so puzzling.
I also tried this:
FullSimplify[2 Cos[1000 t] - 4 Sin[1000 t]] /.
a_ Cos[c_] - b_ Sin[c_] -> Sqrt[a^2 + b^2] Cos[c + ArcTan[a, b]]
The output I get for this is:
2 (Cos[1000 t] - 4 Sin[1000 t])
Clearly there is a match here , yet it doesn't do anything.