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A Variety of Extension 1 Problems - St George Girls High School Trial 2001 (1 Viewer)

Robbie69

New Member
Joined
Oct 16, 2003
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4
Hey guys.
I've been working through the St Geroge Girls High Trial 2001 and
have been having some quite some difficulty throughout the paper.
Question 2
(a) Part (i) and (ii)
(c)
Question 3
(a)(ii)
(b)(iii)
(c)
Question 4
(c)(ii)
Question 5
(a)
Question 6
(a)
(b)(ii)
(c)
Question 7
(b)(iv)

You can find the paper at the Mathematics Extension 1 section of www.boredofstudies.org.
It is towards the bottom and is the 2001 Trial.

If anyone could provide any help in these questions it would be
greatly appreciated.

Cheers.
 
Last edited:

Fosweb

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UNSW. Still.
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HSC
2003
I actually looked at it, got sick of this paper by about Q3, so thats all I did. But here's some hints up to there:

Q2: a)
i: You are given that AB = AG, and since ABCD is a ||ogram, then AB=AG=CD. So you can prove that ACGD is a rectangle, as its diagonals are equal, and thus its cyclic...
ii: Since its cyclic, then AD must be an arc of the circle, and you know a property about angles subtended off the same arc...

2. c)
i. To show this thing is in SHM, you have to prove that <sup>d<sup>2</sup>x</sup>/<sub>dt<sup>2</sup></sub> is in the form -n<sup>2</sup>X. You have an x, and take -4 out the front and it gives you that form straight away, where X = (x-1/4)

ii. Use the formula v<sup>2</sup> = n<sup>2</sup>(a<sup>2</sup> - X<sup>2</sup>). You know X from part i, you are given when v = 0 in the question, sub in, get a = 1.
T = 2pi/n, and you know n, so sub in again.

iii. You could do it a number of ways, but using the standard for for velocity, where v = -ansin(nt) would probably work, since you just found all these things in part ii.

3.
i. Answer is 9!/(4!x2!) = 7560
ii. You need the number of arrangements where it goes like this:
EEEE RR P S V.
So this is like having 5 different letters, so the answer (i think), is the number of ways you can arrange these '5' letters, divided by the answer in part i.
so: 5!/(7560) = 1/63 (this treats all e's and r's as the same letter.)

This is where i got sick of it and stopped:
but for b. iii: at t=0, x=1. lnx > 0 at x > 1, and if x < 1 (but >0) then lnx is negative... think about that.

c) didnt even look at it, looks too long.

Q4, c: ii: Looks like you will need cosine rule

Q5: a) Draw triangles.
Q6: a) Similar triangles...
Q6:
b) use midpoint formula, get your x and y coords, and shove in the result you came up with in i. then solve these x and y coords to give you a locus where you have eliminated p's and q's (which will be done because you put in the part i result)

c) Generally when dividing a polynomial, the remainder has to have a degree of less than the bit you are dividing by, so thus it has form ax + b, as other bit is x^2-7x+12
Other part of this: use remainder theorem, by writing the polynomial something like: p(x) = (x-4)(x-3).Q(x) + R(x), where R(x) is remainder ( i think you can do it like this... also look at the form of R(x) from the 1st bit.)

7. Didnt do any of this. Might look at it later...
 

Robbie69

New Member
Joined
Oct 16, 2003
Messages
4
Thanks heaps for your help!
I just needed the first step to get me going
Question 7 wasn't particularly hard, it was just the very last
question to do with exponential growth that i struggled on.
Probably the easiest question on the whole paper.
With the ease you did the earlier questions, question 7 will
probably be a walk in the park!
Once again thanks for your help.
 

stag_j

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Jul 21, 2003
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Location
Sydney
my answer was 15 for question 7 iv
anyone else get this?
i dont think it was too hard, assuming i did it right.
i just subbed in the known values and solved for t
 

stag_j

Member
Joined
Jul 21, 2003
Messages
95
Location
Sydney
6b) part ii
i got ay=x^2-2x
looks a lil funny to me but its the best i can do...

6c)
p(x)=(x-3)(x-4)Q(x) + (ax+b)
p(3)=3a+b=3
p(4)=4a+b=4
therefore a=1, b=0
so when p(x) is divided by (x-3)(x-4) remainder will be ax+b = x
 

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