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# Official Edexcel C3 Discussion Thread watch

1. (Original post by milliondollarcorpse)
I have a feeling it may have actually been in the AS text book, I'm not too sure though. It definitely is useful to know however and I've seen them sneak it into a few questions before.
are the identities:
sinx= cos(x-pi/2)
cosx= sin(pi/2-x)
?
I have never seen these either.xxx
2. (Original post by indie_couture)
are the identities:
sinx= cos(x-pi/2)
cosx= sin(pi/2-x)
?
I have never seen these either.xxx
I think I learnt these at GCSE level, can't remember exactly.

Anyways it's like this:

If sin 60 = (root3)/2, then cos 60 = (root3)/2

"The sin of an angle is equal to the cos of the complement of that angle."

sin 90 is 1. cos 0 is 1.

cos (100) = -0.173
sin (-10) = -0.173

cos (360) = 1
sin (-270) = 1
3. (Original post by indie_couture)
are the identities:
sinx= cos(x-pi/2)
cosx= sin(pi/2-x)
?
I have never seen these either.xxx
Yep, although is usually written as .

Remember since cos(x) is an even function cos(x)=cos(-x). Therefore it can also be written as
4. Hey does anyone have a link for the solomon papers? I would really appreciate it because I can't find them : (
5. (Original post by Babyblu)
Hey does anyone have a link for the solomon papers? I would really appreciate it because I can't find them : (
http://www.thestudentroom.co.uk/show...4&postcount=20
6. (Original post by jj.)
So if June 09 was easy...does that mean ours will be ridiculously hard? Harder than any paper before...EVER!?
I hope it's a hard paper, because 67/75 for an A is quite a ridiculous grade boundary; especially for people aiming for an A* in Maths/Further Maths.
7. sup guys how's revision for c3 going? I was doing the trig chapter and did the following question. 4tan($) = tan(2$). {0<$<360} btw$ is equal to or greater than zero. I did this by considering that tan(2$)= sin(2$)/cos(2$) can anyone try to do it with the identity for tan(2$),ty. Quote me when your answering ty
8. Just did a paper. Got 71/75. This was 90 UMS in the original sitting.
9. Guys; if it's hard it's good! Low grade boundaries!! As long as you can do some of it obviously, but I'm sure all of the geniuses on here will. Unlike M1 yesterday, which was relatively easy, so any mistakes will lower the UMS loadsssss
10. (Original post by jj.)
So if June 09 was easy...does that mean ours will be ridiculously hard? Harder than any paper before...EVER!?
The problem is with June 2009 was that I swear there were three questions on trigonometry, which was just stupid.
So I'm sure all that means is they will give only one trig question (and probably an "easier" one which nearly everyone will get) and make the paper a lot more varied in terms of content.

Although, didn't exam boards say that now the A* has been introduced they are making papers "harder?" Because this is the first C3 to be introduced to qualify; although that may have just been a spin-line by the media.
11. Yeah a ridiculously hard paper with something like 54/75 to get an A would be beautiful.
12. (Original post by Anti-Derivative)
sup guys how's revision for c3 going? I was doing the trig chapter and did the following question. 4tan($) = tan(2$). {0<$<360} btw$ is equal to or greater than zero. I did this by considering that tan(2$)= sin(2$)/cos(2$) can anyone try to do it with the identity for tan(2$),ty. Quote me when your answering ty

Then just solve both and
13. And yeah, I hope our paper isn't like June 2009. 67/75 for an A? Even the best of students could lose 8 marks on a bad/unlucky day.
14. What's the best way to revise for C3?

Go through the textbook and then past papers?

Or do past papers straight away?
15. (Original post by jj.)
oooh, sorry to quote again, but I just saw your sig and you're retaking C2? Have you taken it yet? If we're allowed to discuss it, was it relatively easier?
Yeah I retook it on Monday! I thought the paper was "harder" than the June one, but I felt better prepared (co-ordinate geometry = RARGH). Only missed out 7 marks versus last year's ten. Hopefully I did better!

And in regards to solomon, I do think they're good practice but I have stated previously that I wouldn't expect to be able to do EVERY question without looking at a mark scheme, because they tend to consist of harder questions than the actual papers do.
16. (Original post by jj.)
That paper was easy though Probably the easiest paper set..I think that was a pretty good boundary... idk though
Yeah but to be honest I naturally lose a few marks unfortunately due to silly errors I make, I'm hoping for about 72 or 73. However as I said on a bad day I think a strong student could lose 8 marks, even if is an easy paper.
17. (Original post by Babyblu)
Hey does anyone have a link for the solomon papers? I would really appreciate it because I can't find them : (
i dont have a link for the solomons..bt if u need them i can upload them..
18. (Original post by jj.)
Well it depends on how everyone does, doesn't it.
Well, define an easy/hard paper? The only way to say whether a paper is difficult or easy is dependant on how everyone taking it does. If the grade boundary is 67/75 for an A, quite obviously it was an easy paper. Hence, for a hard paper, you'd be looking at a grade boundary for an A of around 50/75.
19. (Original post by shereez234)
i dont have a link for the solomons..bt if u need them i can upload them..
Hey it's o.k someone sent me them but thanks anyway!
20. (Original post by gottastudy)
What's the best way to revise for C3?

Go through the textbook and then past papers?

Or do past papers straight away?
Yeah, go through the text book and start to understand the topics! Then start practice papers so you can get used to the format of the papers and timing also!

If you do like all the Solomons and then the edexcel past papers, I can almost guarantee you will get at least an A!!

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