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#1 2008-12-06 03:03:42
- GemmaJ1988
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- Registered: 2008-10-08
- Posts: 39
please help
does anyone know the values of:
i know that:
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#2 2008-12-06 03:41:43
- JaneFairfax
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- Registered: 2007-02-23
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Re: please help
Last edited by JaneFairfax (2008-12-06 03:45:28)
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#3 2008-12-06 04:04:20
- mathsyperson
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- Registered: 2005-06-22
- Posts: 4,900
Re: please help
i actually has four 4th roots. To find them all, plug n = 0, 1, 2, 3 into this:
(Also, another square root of i would be the negative of the one you have)
Why did the vector cross the road?
It wanted to be normal.
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#4 2008-12-06 21:08:32
- GemmaJ1988
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- Registered: 2008-10-08
- Posts: 39
Re: please help
which is equivalent to:
Then i get lost
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#5 2008-12-07 03:47:17
- mathsyperson
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- Registered: 2005-06-22
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Re: please help
I'm guessing Jane's used the half-angle formulas to get those.
Taking x = π/8, we have:
Do a similar thing for the other one by first manipulating sin 2x = 2cosxsinx, then plugging in.
That's all optional extra stuff though, keeping the answer in cos and sin form is perfectly alright.
In fact, in most cases that's what has to happen.
Why did the vector cross the road?
It wanted to be normal.
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