You are Here: Home >< Maths

# Edexcel A2 C3 Mathematics 12th June 2015 watch

1. (Original post by ridirahman)
Attachment 425681

How would you draw that??
I need to draw it to find the domain
You cant really find the domain from a graph in this case, you'd need to know to use common sense that ln(x+2) x+2 cannot be zero as ln0 is undefined

2. (Original post by kdevitto)
http://qualifications.pearson.com/co...c_20100218.pdf

Question 8 here, why does cot2x=0 become tan2x= infinity symbol?
Could someone explain how they solved this? Thanks!
simple! cot 2x is the same as cos2x/sin2x.

So eventually cos2x=0 AND YOU SOLVE!! YOU WILL GET 90,270
3. (Original post by domcandrews)
https://b3755649dbd1afe3db91a899c3b9...%20Edexcel.pdf

Anyone help on Q2 part b, not sure where they're getting the solution from/what to use

MS is here:
https://b3755649dbd1afe3db91a899c3b9...%20Edexcel.pdf

many thanks
i'm guessing you got to cos(2x+(2pi/3)) = 1/2.

Since you're looking for solutions in the range 0<x<pi, if we call 2x+(2pi/3) theta, then the range of theta is 2pi/3 < theta < 8pi/3. At this point you may wish to use a CAST diagram and find all the values, and pick out the ones in the range before finding the x values.
4. (Original post by BioAgent)
For the Rcosalpha/Rsinalpha questions do you have to show all your working?
why risk it? show all working!
5. (Original post by domcandrews)
count me in too, started today and haven't looked at c3 since we finished it back in november, this is going to be fun loooool
Nah I'm messing up the studentroom's high scoring pattern
6. (Original post by kdevitto)
http://qualifications.pearson.com/co...c_20100218.pdf

Question 8 here, why does cot2x=0 become tan2x= infinity symbol?
Could someone explain how they solved this? Thanks!
cot = cos/sin

cos = 0

2x = cos-1(0)
7. (Original post by Ripper Phoenix)
Youll be relieved that proving by counter and stuff isnt on edexcel syllabus. Edexcel can not bring stuff outside the spec. It would result in a petition. But anyway good luck 👌🏼

Posted from TSR Mobile
Ah thank you! I wouldn't have known, but it's not that bad actually but cheers for the heads up!
8. Anyone got the jan 2015 ial paper?
9. (Original post by frozo123)
Nah I'm messing up the studentroom's high scoring pattern
AHAHA yesss
10. (Original post by Cosmi)
http://www.examsolutions.net/a-level...6&solution=8.2

Why isn't cos() -1? Surely -21/25 is smaller than 21/25?
Anyone able to help with this? I've never understood this.
11. (Original post by Mrkingpenguin)
Anyone got the jan 2015 ial paper?
12. How THE FUDGE is part a (i) the graph of f^-1(x) ?

i thought to draw the inverse function you reflect the f(x) in the y=x line.
Rather than imagining it through the head, is it possible to just times the co-ordinates by something to find the reflection in the y=x line Because i do not understand how they got that in part a (i)

Someone help!
Attached Images

13. (Original post by Mrkingpenguin)
Anyone got the jan 2015 ial paper?
14. (Original post by Humbers)
I feel like a butchered the answer but i got there in the end, if theres a quicker way that i missed, tell me
Attachment 425677
thanks guys
15. (Original post by Mrkingpenguin)
Anyone got the jan 2015 ial paper?

Think they combine c3/c4
16. (Original post by SeanFM)
i'm guessing you got to cos(2x+(2pi/3)) = 1/2.

Since you're looking for solutions in the range 0<x<pi, if we call 2x+(2pi/3) theta, then the range of theta is 2pi/3 < theta < 8pi/3. At this point you may wish to use a CAST diagram and find all the values, and pick out the ones in the range before finding the x values.
Nope i don't understand how they got to that first bit with cos(2x + 2pi/3)??? Am i missing something silly or...?
17. (Original post by Mrkingpenguin)
Anyone got the jan 2015 ial paper?
its a c34 paper not a c3 paper on its own
18. (Original post by studentwiz)
someone help
19. (Original post by domcandrews)
Nope i don't understand how they got to that first bit with cos(2x + 2pi/3)??? Am i missing something silly or...?
It's linked to part a. Sec(x+(pi/6)) is the same as 1/(cos(x+(pi/6)), so they've multiplied both sides by cos(x+(pi/6)) to get something of the form in part a.
20. How the FUDGE is part a (i) the graph of the inverse function? i thought the inverse function is a reflection in y=x line and i just can't see that with this graph in my head.
Is there a way in which you can just times the co-ordinates by something to find the reflection in the y=x line??? Someone please help!
Attached Images

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 21, 2016
Today on TSR

### Cambridge interviews

Find out who is getting invitations

### University open days

• Heriot-Watt University
School of Textiles and Design Undergraduate
Fri, 16 Nov '18
• University of Roehampton
Sat, 17 Nov '18
• Edge Hill University
Faculty of Health and Social Care Undergraduate
Sat, 17 Nov '18
Poll
Useful resources

Can you help? Study help unanswered threadsStudy Help rules and posting guidelinesLaTex guide for writing equations on TSR

## Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE