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# Further maths help with the argand diagram watch

1. Given that Modulus( z + 2 - 2root(3)) = 2
Find the min and max of arg z.
I got pie/2 for the min and 5pie/6 for max
According to the book the max is wrong how would I work it out. The actual answer is 2.51 rad
2. (Original post by Balkaran)
Given that Modulus( z + 2 - 2root(3)) = 2
Find the min and max of arg z.
I got pie/2 for the min and 5pie/6 for max
According to the book the max is wrong how would I work it out. The actual answer is 2.51 rad
Assuming you mean | z + 2 - 2root(3)i | = 2 (you missed out the i), then I agree with you. It's worth noting that 5pi/6 is 2.61799... radians, so it's not completely impossible that there was a small transcription error, although why they wouldn't give an exact value I have no idea.

[Fully expecting someone to point out that this isn't right after all...]
3. (Original post by Pangol)
Assuming you mean | z + 2 - 2root(3)i | = 2 (you missed out the i), then I agree with you. It's worth noting that 5pi/6 is 2.61799... radians, so it's not completely impossible that there was a small transcription error, although why they wouldn't give an exact value I have no idea.

[Fully expecting someone to point out that this isn't right after all...]
I also thought it was an error but it is the official edexcel AS core pure book so I thought I was wrong. I'll ask my teach to be 100% sure. Thanks for the help.

Also yeah it was mean to be 2root(3) i
4. (Original post by Balkaran)
I also thought it was an error but it is the official edexcel AS core pure book so I thought I was wrong. I'll ask my teach to be 100% sure. Thanks for the help.

Also yeah it was mean to be 2root(3) i
Is this the new version? Core Pure Mathematics Book 1/AS? I've got a copy of that I can check out on Monday. Which page is it on? Thanks!
5. (Original post by Balkaran)
I also thought it was an error but it is the official edexcel AS core pure book so I thought I was wrong.
It is also worth noting that errors in text books are far from rare. When you consider the number of different text books that publishers are churning out to meet the new course requirements, the fact that accreditation happened fairly late in the day for Edexcel, and the shear number of problems in each text book, this is almost inevitable.

If errors can slip through on actual exam papers, then it should be no surprise that it happens in text books.
6. (Original post by Pangol)
Is this the new version? Core Pure Mathematics Book 1/AS? I've got a copy of that I can check out on Monday. Which page is it on? Thanks!
It's exercise 2E
Page 34
Question 5

Yeah this is the new version the green book with the butterfly on it.
7. (Original post by Pangol)
It is also worth noting that errors in text books are far from rare. When you consider the number of different text books that publishers are churning out to meet the new course requirements, the fact that accreditation happened fairly late in the day for Edexcel, and the shear number of problems in each text book, this is almost inevitable.

If errors can slip through on actual exam papers, then it should be no surprise that it happens in text books.
The textbook does have an online solution bank, but I can't get the website to load at the moment unfortunately.
8. (Original post by Balkaran)
Given that Modulus( z + 2 - 2root(3)) = 2
Find the min and max of arg z.
I got pie/2 for the min and 5pie/6 for max
According to the book the max is wrong how would I work it out. The actual answer is 2.51 rad
You are correct. This question was in an old textbook and here is the solution:

9. (Original post by Notnek)
You are correct. This question was in an old textbook and here is the solution:
Yeah, that is exactly what I (and, I have no doubt, the OP) thought. Thank you!
10. There are far too many mistakes in the new further maths text book. The question tells you one thing and the answer tells you, you are wrong. You look at the solution bank on the internet and find that they didnt even do the correct question so now you are stuck with the wrong question and the wrong answers. Look at chapter 9 vectors mixed exercise question 21a)

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