How do you derive a formula for both and ? Do you just use the sum and difference formulas?

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- Feb 28th 2009, 02:39 PMchrozer[SOLVED] Deriving a Formula
How do you derive a formula for both and ? Do you just use the sum and difference formulas?

- Feb 28th 2009, 02:57 PMstapel
What do you mean by "deriving" the "formulas"? Are you supposed to restate the expressions in terms of and ?

Thank you! :D - Feb 28th 2009, 03:07 PMchrozer
- Feb 28th 2009, 03:08 PMHallsofIvy
Assuming you mean what stapel suggested, that is writing them in terms of , , then, yes. You use the sum formulas.

So

and use the formulas above.

Similarly for

and . - Feb 28th 2009, 03:16 PMchrozer