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# Edexcel A2 C3 Mathematics 12th June 2015 watch

1. (Original post by harrisondg)
growl all you want YOU ARE STILL A DUMMY
ahahhah wow!!!!!!!! Jeez Someone's upset?
2. (Original post by Ripper Phoenix)
why have you worked from right to left? is that even allowed? i thought its always prove left to right
A proof is still a proof, regardless of which side its from. It's usually best to take the most complex side. I do both! I take one side and start breaking it down into other forms, until I can get it into some sort of form which is the same as either side I'm working on. So my work can be pretty messy sometimes. But it's a valid way to do it.
3. (Original post by Ripper Phoenix)
why have you worked from right to left? is that even allowed? i thought its always prove left to right
Yes absolutely it's allowed, if you've shown one equals the other, you've shown that the two identities are equal, it doesn't matter at all which way round you put it, you've still shown they are equal. If you see a way from right to left, do it that way! You could have done it the other way round though but I just think that was the easiest way for me to see in the exam.
Trig identity: how i did it...
split thing into 1/cos2x + sin2x/cos2x
then make common denominator of cos2x so it is (1+sin2x)/cos2x
then expand the double angle formulae so (1+2sinxcosx)/(cosx)^2 -(sinx)^2
then factorise denominator (diff of 2 squares) so
(1+2sinxcosx)/(cosx + sinx)(cosx - sinx)
using identity (sinx)^2 + (cos)^2 =1, sub in the sin and cos parts so you get
((sinx)^2 +(cosx)^2) +2sinxcosx)) / (cosx + sinx)(cosx - sinx)
the numerator can be factorised to (cosx+sinx)(cosx +sinx),
so now u have (cosx+sinx)(cosx +sinx) / (cosx + sinx)(cosx - sinx)
and then one of the (cosx + sinx) brackets cancel with the one on the bottom leaving u with (cosx + sinx) / (cosx -sinx)
sorry for it being hard to read...
thanks
5. Damn, I just realised I misread the last question, 9c, and thought it was asking if it was minimum or maximum >_<

Would I get a mark if I said k was negative so the result would be a positive? I know for sure if I read it right I'd get it right because I know it would be increasing because it's a positive gradient.
6. 57 for A* june 2013 ...
but is june 2015 as hard as 2013???
7. Did anyone get tanA=1/3

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9. (Original post by kprime2)
I would agree it was trickier compared to previous years papers (except June 13 which was harder by miles). All I'm saying is that there was nothing on that paper which would have thrown a well prepared candidate off. My further maths class found it to be a reasonable paper.
My further classmates and I found it a weird paper. Best way to describe it I think.
It wasn't "insanely hard" but had a number of tricky questions and some rarely seen aspects e.g. Q1 threw me and many others I know at first. I myself didn't spot the difference of two squares on 8a and kicked myself.
Though I know my other friends who only do base maths found it quite hard so I reckon the boundaries'll be lower than average, but not quite as low as 2013.
10. (Original post by JuniorXX)
57 for A* june 2013 ...
but is june 2015 as hard as 2013???
personally, i don't know if you will agree but I thought june 2013 had parts that very very hard and some quite easy, but june 2015 seemed to be all tricky and easy to loose marks so I would of said they will appear the same but who knows hey!
11. Generally i thought this paper was nice (compared to the m1 and my other exams) so i walked out of that exam pretty confident... Then i hear that there were NINE QUESTIONS and i only answered eight... I was so angry at myself. Can someone tell me that the last questions wasnt worth that many marks?
http://www.thestudentroom.co.uk/show....php?t=3399381
13. Did anyone get 0.91 at any point in that exam? :P
14. Added to the OP, not that anyone looks.
15. (Original post by Seventeen)
the equation of the asymptote for the first graph was y=-5, was there an asymptote for the second graph? If so what was the equation.
Y=5
16. (Original post by André3000)
Hi, I also had a brain freeze but I got it as 3cosx +sinx and put it in Rcos(x+a) form- I know I got thr right answers but will I still get the marks for not using tan?
I did it this was as well, cant remeber my answer but hope theres a couple method marks :/
17. (Original post by TheFuhrer)
73 or 33?!!!
18. (Original post by Zeus579)
I forgot to write the asymptote. Would just lose 1 mark each?
Me too. Yes I think we will lose 2 marks for this.
19. Lost 5 marks according to the unofficial MS
20. (Original post by raypalmer)
Did anyone get tanA=1/3

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I didn't myself. Though I think if you went that route it would've been a minus.I didn't want to cancel through (because that eliminates solutions) but I couldn't see how to do it. In the end I settled for transforming it into Rcos(x-alpha).Though I still only got 2 solutions but they seem to match the mainstream answers.

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