i need to prove sinx-siny= 2 sin( (x - y)/2 ) cos( (x + y)/2 )
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here is a simple say. for some x and y.
after applying the sine addition and subtraction formulas, , you will end up with now note that we want this in terms of a and b so we have and so using this we have
This is a rehash of putnam120's solution . . . with baby steps. Prove: .
We have these two formulas: . . . .
Subtract (2) from (1): .
Then (3) becomes: .
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