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AEA Mathematics 25/06 2013 Thread

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Original post by yl95
I got 7 solutions or something for theta...looks like it's a fail for me.


Oh... I think this sounds right actually. I got one solution as being something like 3Th = 54+360n and the other as Th=70, and forgot to subtract from 180 degrees or whatever it should have been so I probably missed a few solutions.
Reply 161
Original post by Math-Magician
The expansion would be valid, but (1+aX)^1 = 1+aX, and (1+aX)^0 = 1, so they both give no X^2 or X^3 terms and I'm sure the question said the coefficients of these were non-zero? The next part then asked you to reject one of the other two solutions (as they told you X=1/2 and this made mod(aX)>1)

I definitely got 5/2 and -1/2 though so that's good!
I'm pleased if you got four solutions for theta as I thought I'd included spurious solutions or something, it looked like there were too many :s-smilie:

I must have dropped 20-30 marks or so on this paper, plus all the style marks no doubt :s-smilie:


aaah I missed the non-zero part. I'm confused about trig solutions will need to double check, I think I may have had more than 4,was it x+17
x+8?
I'm hoping I didn't drop more than 30
(edited 10 years ago)
Original post by jarasta
aaah I missed the non-zero part. I'm confused about trig solutions will need to double check. was it x+17
x+8?


That rings a bell, but I have no idea about the actual answers, I just made up some numbers before to show what I did wrong!

Plot the two graphs on the computer and see where they cross if you want to be sure.
(edited 10 years ago)
I got 16 degrees for one of my theta values, I think...
Reply 164
Original post by Math-Magician
Oh... I think this sounds right actually. I got one solution as being something like 3Th = 54+360n and the other as Th=70, and forgot to subtract from 180 degrees or whatever it should have been so I probably missed a few solutions.

Yeah I had the initial solution, y+360n
the (180-y)+360n
Reply 165
Original post by yl95
I got 16 degrees for one of my theta values, I think...


yeah I came out with 16.
Ill show what I did
2sin(x+17)=cos(x+8)/cos(x+17)
2sin(x+17)cos(x+17)=sin(90-(x+8))
sin(2x+34)=sin(82-x)
so 2x+34=82-x... find 3x. then +360n divide by 3
then 180-3x+360n, divide by 3
Oh, I did +180n...ugh.
Original post by jarasta
yeah I came out with 16.
Ill show what I did
2sin(x+17)=cos(x+8)/cos(x+17)
2sin(x+17)cos(x+17)=sin(90-(x+8))
sin(2x+34)=sin(82-x)
so 2x+34=82-x... find 3x. then +360n divide by 3
then 180-3x+360n, divide by 3


I just did it on an online graphing calculator and it looks like there should be 3 solutions :s-smilie:

Oops, I forgot to put it into radians, I'm getting Theta = 16, 64, 136, 256 using the first line of your post.

Try it on here but remember to put it into radians first:
https://www.desmos.com/calculator
(edited 10 years ago)
Oh no! How much would I be penalised for extra solutions using +180n?
Reply 169
Original post by Math-Magician
I just did it on an online graphing calculator and it looks like there should be 3 solutions :s-smilie:

Oops, I forgot to put it into radians, I'm getting Theta = 16, 64, 136, 256 using the first line of your post.

Try it on here but remember to put it into radians first:
https://www.desmos.com/calculator

I got 4 from the graph, if i put the right things in and I remember getting those numbers
Did anyone have a complete solution to the series one, not to double check what I did
(edited 10 years ago)
My brain was utter mush, I don't think I managed to finish any of the final parts. No distinction for me.
Original post by Appeal to reason
My brain was utter mush, I don't think I managed to finish any of the final parts. No distinction for me.


Im thinking that the grade boundaries for a distinction might be closer to 70 than 80 this year given that a lot of people who would otherwise have scored well will have sat STEP first and then done worse in the AEA. :dontknow:
Reply 172
grade boundary poll?
Reply 173
Original post by Math-Magician
Im thinking that the grade boundaries for a distinction might be closer to 70 than 80 this year given that a lot of people who would otherwise have scored well will have sat STEP first and then done worse in the AEA. :dontknow:

I hope so, or that Warwick will take me with a merit given I get the A-levels grades I'm hoping for. A guy from last year got in with a Merit, so fingers crossed!
(edited 10 years ago)
Original post by jarasta
I hope so, or that Warwick will take me with a merit given I get the A-levels grades I'm hoping for.


Didn't you take STEP I yesterday? I'm sure you'll have done enough to get into Warwick :biggrin:
When are we allowed to talk about STEP?
Original post by Math-Magician
Im thinking that the grade boundaries for a distinction might be closer to 70 than 80 this year given that a lot of people who would otherwise have scored well will have sat STEP first and then done worse in the AEA. :dontknow:


Its been close to 70 nearly every year?
Original post by Math-Magician
When are we allowed to talk about STEP?


I think its 1pm
Original post by Appeal to reason
Its been close to 70 nearly every year?


Oh really? Maybe it'll go even lower :colone:

Original post by MathsNerd1
I think its 1pm



Ah, thanks. I'm going out so I have to wait until later. :cool:
(edited 10 years ago)
Original post by MathsNerd1
I think its 1pm


Ah, thanks. I'm going out so I have to wait until later. :cool:

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