2014 Extension 2 BOS Trial Exam Discussion Thread (1 Viewer)

[mreditor16]

i constructed a quadrilateral using the points z, z+1, 1, and 0. and since it's a parallelogram, where the diagonal bisects the base angle, it must be a rhombus -> |z| = 1

obviously with exception z = -1 because then it's not a quadrilateral

hmm okay, anyone do it sorta algebraicly?

 

[Carrotsticks]

i constructed a quadrilateral using the points z, z+1, 1, and 0. and since it's a parallelogram, where the diagonal bisects the base angle, it must be a rhombus -> |z| = 1

obviously with exception z = -1 because then it's not a quadrilateral

It was a circle.

 

[mreditor16]

It was a circle.

Carret, would you have done it how aDimtri did it? Is there any neat algebraic way?

 

[faisalabdul16]

11e) was posted on one of the marathon threads recently (before BOS trials)

 

[Hi there444]

Hey all, I did the exam today at home. If anyone would like to compare or discuss answers, here are mine:

View attachment 31002.

I didn't include the three questions I drew diagrams for (two graphing q's and the circle geometry), I might do them in paint tomorrow lol...don't have a scanner.

I also didn't include every step of my working in this, so please ask if anything is unclear or if I just made sillies/typoes.

Ahhhh I cant see glittergal. Divine light is burning my eyes ahhhh.

 

[Tugga]

Carret, would you have done it how aDimtri did it? Is there any neat algebraic way?

if you let z=x+iy and then use tan definition of arg it works out

 

[Hi there444]

It was a circle.

Was that the locus one? bahahahah idont know why I got x^2+y^2 =1 .I started day dreaming in the middle of the test for the rest of the test. I saw carrots face when hed looked at me and he was just like 'do some math and stop dreaming'. What to do- need my energy drink quota everyday ....

 

[Hi there444]

Carret, would you have done it how aDimtri did it? Is there any neat algebraic way?

I failed this test. I threw away all my chances of getting a good mark in 4u. What would you do for integration one? I had no idea? I tried every kinda manipulation but in the end got tired of trying.
Edit: the first one.

 

[aDimitri]

It was a circle.

yes...
i said |z| = 1

 

[mreditor16]

if you let z=x+iy and then use tan definition of arg it works out

oh probs abandoned it too early :/

 

[mreditor16]

I failed this test. I threw away all my chances of getting a good mark in 4u. What would you do for integration one? I had no idea? I tried every kinda manipulation but in the end got tired of trying.
Edit: the first one.

I haven't tried the test yet. I was only asking about 11 e) just then, because a non-BOS friend emailed me asking how to do the question. and I recognised it from when I looked through the 4u bos trials

 

[aDimitri]

11.e) was actually the exact opposite of question 2.e) in HSC 2003.
http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2003exams/pdf_doc/mathematics_ext2_03.pdf

 

[Carrotsticks]

Carret, would you have done it how aDimtri did it? Is there any neat algebraic way?

Not that I know of, using vectors is extremely straightforward.

11e) was posted on one of the marathon threads recently (before BOS trials)

11.e) was actually the exact opposite of question 2.e) in HSC 2003.
http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2003exams/pdf_doc/mathematics_ext2_03.pdf

What a coincidence! I did not know that.

Whoever wrote that problem probably had the same mindset as me, wanting to screw over those who blindly sub in z=x+iy.

 

[aDimitri]

Not that I know of, using vectors is extremely straightforward.





What a coincidence! I did not know that.

Whoever wrote that problem probably had the same mindset as me, wanting to screw over those who blindly sub in z=x+iy.

i did the 2003 paper on thursday so when i saw it in BOS trials it was a good moment

 

[Immortality]

yes...
i said |z| = 1

Wouldn't the locus be the circle |z|=1 as well as the ray x>-1 where x=/=0?

 

[aDimitri]

Wouldn't the locus be the circle |z|=1 as well as the ray x>-1 where x=/=0?

uhh no that doesn't work but come to think of it you are right that there should be more than just the circle. it works for the entire real axis except for -1 <= x <= 0

 

[Carrotsticks]

Currently marking the paper, the highest mark for Question 16 is 14/15.

 

[Hi there444]

Currently marking the paper, the highest mark for Question 16 is 14/15.

Beastly.

 

[mreditor16]

Currently marking the paper, the highest mark for Question 16 is 14/15.

oh wow!

 

[Trebla]

Currently marking the paper, the highest mark for Question 16 is 14/15.

Meanwhile for Question 15...