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# Maclaurins series watch

1. If the first 3 terms in the expansion of ln(cosx+sinx) = x-x^2+(2/3)x^3
How do you automatically know hat ln(cosx-sinx) = -x-x^2-(2/3)x^3
2. you can rewrite ln(cosx-sinx) as ln ( cos(-x) + sin( -x ) )

because of the odd/even thing with sin & cos
3. (Original post by the bear)
you can rewrite ln(cosx-sinx) as ln ( cos(-x) + sin( -x ) )

because of the odd/even thing with sin & cos
Of course. Seems so simple now. I just could not see it.

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Updated: October 22, 2015
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