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# FP2 Roots of unity watch

1. how do you do the 1ii) this thing has always confused me the screens are a bit upside down thanks for the help in advance,
how do you do the 1ii) this thing has always confused me the screens are a bit upside down thanks for the help in advance,
Sorry, those images hurt my eyes

Is the 2nd pic supposed to be your working for the problem?

If you've found the modulus r and the argument so you have written , then the principal cube root is for example.
3. After you have the principle cubed root, note that theta=theta+2pi=theta+4pi
4. (Original post by aznkid66)
After you have the principle cubed root, note that theta=theta+2pi=theta+4pi
I know what you mean, but that's not literally true is it?
5. Well, I don't see how it's not. They represent the same point on the unit circle ._.

EDIT: But yes, I guess it would be better to say that they are equivalent angles rather than equal values.
6. (Original post by aznkid66)
Well, I don't see how it's not. They represent the same point on the unit circle ._.

EDIT: But yes, I guess it would be better to say that they are equivalent angles rather than equal values.
Yes, the point is that exp(i x angle2) = exp(i x angle1) etc, not that the angles are equal
7. But the angles are equal; theta radians is always equal to theta+2pi radians, even outside of Euler form ._.
8. (Original post by aznkid66)
But theta radians is always equal to theta+2pi radians, even outside of Euler form ._.
i think we're arguing semantics now

Rotation through one angle produces the same effect as rotation through another angle. I personally would not write angle1 = angle2 in this case.

I appreciate you understand what is going on, but an unsympathetic examiner might not, so I would err on the side of caution and write something like:

to be explicit about what I'm arguing in an exam.
9. (Original post by davros)
i think we're arguing semantics now

Rotation through one angle produces the same effect as rotation through another angle. I personally would not write angle1 = angle2 in this case.

I appreciate you understand what is going on, but an unsympathetic examiner might not, so I would err on the side of caution and write something like:

to be explicit about what I'm arguing in an exam.
so would one of the answers for question 1ii) e^(7/4pi)?
so would one of the answers for question 1ii) e^(7/4pi)?
I haven't worked through the question in detail, but isn't 7pi/4 the argument of the original number and not one of the cube roots?

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Updated: March 24, 2013
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