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October 26th, 2013, 10:32 AM   #1
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Complex Numbers question (de Moivres)

Can anyone help me with this problem? In the attached photo, I have highlighted the area I need help with. I don't understand what happens to the ^1/4 , and how it changes the other numbers. - e.g.: why does the 2n(pi) change to pi(n)/2
I have an idea of what happens, but I would like a proper explanation and why it happens so I can know it better.
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October 26th, 2013, 10:58 AM   #2
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Re: Complex Numbers question (de Moivres)

DeMoivre's formula says that:



This also works for 1/n in the sense that:



So, the 1/4 has gone inside the sin and cos.
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October 26th, 2013, 11:55 AM   #3
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Re: Complex Numbers question (de Moivres)

Quote:
Originally Posted by Pero
DeMoivre's formula says that:



This also works for 1/n in the sense that:



So, the 1/4 has gone inside the sin and cos.
Thanks I understand now, it actually says that in my book but I was getting confused by the 2nPi in general polar form
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