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# FP2 transforming in the complex plane Watch

1. For c I've shown that arg(w+1+2i)=pi/4 however the answer says it's 3pi/4

For d I've shown that z+2=1/w by rearranging to find z and adding on +2 however i can't seem to get arg(w)=-PI/4

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2. Sorted part c.
For d i get arg(1)-arg(w)=pi/4

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3. (Original post by Mutleybm1996)
Sorted part c.
For d i get arg(1)-arg(w)=pi/4

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for c factorize the -i out

split the arg

arg(-i) = -pi/2

-pi/2 + arg(w+1+2i) = pi/4

edit too late
4. (Original post by TeeEm)
for c factorize the -i out

split the arg

arg(-i) = -pi/2

-pi/2 + arg(w+1+2i) = pi/4

edit too late
Argh, being so stupid! I've just realised how to do d too thanks though

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5. (Original post by Mutleybm1996)
Sorted part c.
For d i get arg(1)-arg(w)=pi/4

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for d

z+2 = 1/w
arg(z+2) = arg(1/w)
pi/4 = arg(1/w)
pi/4 = -arg(w)
argw = -pi/4
6. (Original post by TeeEm)
for d

z+2 = 1/w
arg(z+2) = arg(1/w)
pi/4 = arg(1/w)
pi/4 = -arg(w)
argw = -pi/4
Could you possibly have a look at 4c/d? My working is attached

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7. (Original post by Mutleybm1996)
Could you possibly have a look at 4c/d? My working is attached

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I can only see (c) and I disagree (I think)
8. (Original post by TeeEm)
I can only see (c) and I disagree (I think)
Could you possibly provide a hint?

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9. (Original post by Mutleybm1996)
Could you possibly provide a hint?

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second line from the bottom

in the LHS i think you lost the denominator
10. (Original post by TeeEm)
second line from the bottom

in the LHS i think you lost the denominator
So i now have 1=mod(iw-2w+2i)
Any advice on where to go from here?
Would i say 1=mod(i(w+2)-2w)?

Weird, the Book says the answer is mod(w-1/5 (-2+4i))=1/sqrt5

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11. (Original post by Mutleybm1996)
So i now have 1=mod(iw-2w+2i)
Any advice on where to go from here?
Would i say 1=mod(i(w+2)-2w)?

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it is a nasty circle

either put w=u+iv and simplify

or

factorize the coefficient of w
then pull it out of the mod

etc

harder
12. (Original post by TeeEm)
it is a nasty circle

either put w=u+iv and simplify

or

factorize the coefficient of w
then pull it out of the mod

etc

harder
Well now I have absolutely no idea!
Sorry...I'm probably just being useless

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13. (Original post by Mutleybm1996)
Well now I have absolutely no idea!
Sorry...

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it is correct so far

|A(u,v) + iB(u,v)| = 1

SRoot(A2+B2) = 1

square both sides etc
14. (Original post by TeeEm)
it is correct so far

|A(u,v) + iB(u,v)| = 1

SRoot(A2+B2) = 1

square both sides etc

Is this any closer?

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15. (Original post by Mutleybm1996)

Is this any closer?

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If you supply an email address and I will post the solution (2 methods)
16. (Original post by Mutleybm1996)

Is this any closer?

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look at the alternative method in purple
(this approach is a bit hard for students generally)
17. (Original post by TeeEm)
look at the alternative method in purple
(this approach is a bit hard for students generally)
I understand the principle, whether I'd be able to reproduce it is another matter!
Thanks, I may post again if I get stuck on 4d

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18. (Original post by Mutleybm1996)
I understand the principle, whether I'd be able to reproduce it is another matter!
Thanks, I may post again if I get stuck on 4d

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my pleasure
19. (Original post by TeeEm)
my pleasure
Hi, for d I managed to find and plot the two points easily enough, however don't quite understand what the 3pi/4 has to do with the problem?

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20. (Original post by Mutleybm1996)
Hi, for d I managed to find and plot the two points easily enough, however don't quite understand what the 3pi/4 has to do with the problem?

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I have not got a clue which question you are referring to ...

post the workings for this question

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