Proving Trigonometric Identities (page 2 of 3)


This is how the textbook authors come up with those magical proofs, where you wonder how on earth they ever came up with one or another of the steps. There will be times you'll need to do this. But, for your hand-in work, make sure you do the work the right way: Work down one side to the meeting place, and then hop over to the other side and work back up to the starting place. Only by showing your steps in that way will your proof be valid.

...and that's what I needed to end up with. Putting it all together:

In addition to the "working on the more complicated side" and the "converting to sines and cosines" tricks, there is one other trick that hardly ever comes up, but you might want to be familiar with it....


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