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AQA Core 3 - Jan 15th 2010

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I'm good for AQA C3. I only have a problem with one thing which is Trig identities.

Things like Cot2x and Tan2x = 1 and those sorts of things. Does anyone know these or know a website with them on?

Reply 21

Vikki =]

bluemoon05

I'm good for AQA C3. I only have a problem with one thing which is Trig identities.

Things like Cot2x and Tan2x = 1 and those sorts of things. Does anyone know these or know a website with them on?

easiest way to remember the trig identities is just look at sin^2x + cos^2x = 1 then divide by sin^2x to give 1 + cot^2x = cosec^2x or divide by cos^2x to give tan^2x + 1 = sec^2x

:smile:

Reply 22

TLDR

I'm not a fan of posting on forums for help, but I have been defeated by integration by substitution :s-smilie:

Can anyone describe a plain and simple method?
(though my downfall is probably all the rearranging and spotting things)

I get as much that the general idea is making a more simple integration by getting rid of the x terms and you have to stick a dx/du on the end (assuming you're using u terms) but... why?! :confused:

In fact, scrap this, there's a whole thread for it: http://www.thestudentroom.co.uk/showthread.php?p=23009652&highlight=aqa+integration+by+substitution#post23009652

Reply 23

michelle_mishmash

'Vikki

']easiest way to remember the trig identities is just look at sin^2x + cos^2x = 1 then divide by sin^2x to give 1 + cot^2x = cosec^2x or divide by cos^2x to give tan^2x + 1 = sec^2x

:smile:

dats a gd was of rememberin those identities... x

Reply 24

Vikki =]

michelle_mishmash

dats a gd was of rememberin those identities... x

It's not really a way of remembering them, that's where they actually come from so you can just quickly work that out if you ever can't remember them or need to check if they're right.

Reply 25

michelle_mishmash

yh i know.. i just never knew that was how you derive those identities..

Reply 26

michelle_mishmash

are u guys ready for C3??
i am.. but when ever i do past papers i make silly mistakes....

Reply 27

Vikki =]

Yeah I am, I've got fp1 too before then though... But I agree on the silly mistakes as I seem to be getting either 73 or 74 out of 75 on a lot of papers due to something really stupid.

Reply 28

Wednesday Bass

'Vikki

']Yeah I am, I've got fp1 too before then though... But I agree on the silly mistakes as I seem to be getting either 73 or 74 out of 75 on a lot of papers due to something really stupid.

FP1's on Wednesday? I have to do FP1 on Wednesday as it clashses with Stats.
C3's going ok, but I keep forgetting little things when I'm doing past papers. =/

Reply 29

Vikki =]

Wednesday Bass

FP1's on Wednesday? I have to do FP1 on Wednesday as it clashses with Stats.
C3's going ok, but I keep forgetting little things when I'm doing past papers. =/

Yeah FP1 is on Wednesday - PM. S1 is also on Wed, unless you mean S2 which is the week after.

Reply 30

Adam92

Weeman5872

Same. Though, I have a clash witgh M1B. So I have to do M1B afterschool. mlia

Strange thing is, I'm finding C3 the easiest of the main modules so far o.O

Me too, for both parts of this lol. I'm the only person doing M1b and C3 as well so I'll be alone :erm:

Weeman5872

Yeah C1 C2 etc. Yeah they're not bad, the only one im putting off is Decision 1. I've been meaning to revise for it but its so boring! (D2 is surprisingly better than D1)

I think D2 is so much easier than D1 :/. D1 is the worst module everrrrrrr.

Reply 31

cfc18

has anyone done the june 09 core 3 paper yet? .....if so is the mark scheme online ive looked everywhere and cant find.

Reply 32

russell_chan

y = 2/(1 + u)

whats dy/dx ????

Reply 33

cfc18

umm i really dont havea clue have you tried quotient rule perhaps , is this of any of the past papers as i dont remember this question.

Reply 34

Anna2206

russell_chan

y = 2/(1 + u)

whats dy/dx ????

Use the quotient rule.

(vdu/dx - udv/dx)/v^2

u= 2
v= 1 + u

du/dx= 0
dv/dx= 1
vdu/dx= 0
udv/dx= -2(1+u)^-2
v^2= (1+u)^2

Then just piece it together.