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# I need help with a question on FP2 complex numbers :( watch

1. I'm just trying to do part 2 of a question on complex numbers. The first part asked to show that . I did that without a problem, but now it says "hence solve, in the interval 0 <= x <= 2pi, . My problem is that I don't even remember doing this type of questions, I did things like , but I just don't know how to do this one. Can anyone start me off?
2. Assuming that the first part was

The question is

with factorization you will get the solutions.
3. (Original post by ztibor)
Assuming that the first part was

The question is

with factorization you will get the solutions.
Thanks a lot man, it really helps. I did: . I already know that x = 0, Pi/4, Pi, 5Pi/4 and 2Pi, but what about ? I'm not sure how to approach this part, it looks like , how can i solve it?
4. (Original post by Draggy)
Thanks a lot man, it really helps. I did: . I already know that x = 0, Pi/4, Pi, 5Pi/4 and 2Pi, but what about ? I'm not sure how to approach this part, it looks like , how can i solve it?
Since you are told that x is in the range 0 to 2pi, x must be a real angle, so that particular factor has no zeros!
5. (Original post by Draggy)
...
has no real solutions.

Also, you are missing some solutions to the factor . There are 4 of them in the given interval.
6. (Original post by davros)
Since you are told that x is in the range 0 to 2pi, x must be a real angle, so that particular factor has no zeros!
Right, so are these five angles the only ones to be found?
7. (Original post by Draggy)
Right, so are these five angles the only ones to be found?
See my previous post - there are 7 in all.
8. (Original post by ghostwalker)
See my previous post - there are 7 in all.
Ok, from sinx = 0 we get 0, Pi and 2 Pi. I think I did the other one wrong, gives Pi/4 and 3Pi/4. I'm looking at the CAST diagram and can't find the other two.
9. (Original post by Draggy)
Ok, from sinx = 0 we get 0, Pi and 2 Pi. I think I did the other one wrong, gives Pi/4 and 3Pi/4. I'm looking at the CAST diagram and can't find the other two.
10. (Original post by ghostwalker)
Ah, completely forgot about that... The other two angles are 5Pi/4 and 7Pi/4. Thanks a lot for help guys, I feel like I understand all of this now.
11. (Original post by Draggy)
...
FYI.
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