Edexcel A2 C3 Mathematics 12th June 2015 Watch

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bbadonde2
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#681
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#681
(Original post by randlemcmurphy)
Are you planning on remembering identities such as:
cos(x)=sin(90-x)
sin(x)=cos(90-x)
sin(-x)=-sin(x)
cos(-x)=cos(x)
(The bottom two are rather easy to remember)
These are obvious if you know your graphs, learn the graphs not these!
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Cosmi
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#682
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(Original post by bbadonde2)
As the domain of t is 0 to 12. The way the sine graph is your next solution would be like 14 hours. Look at this but it's hard to explain on here! https://07a69ccf283966549a9350d1a669...%20Edexcel.pdf
I understand now. I forgot that the domain of t alone is 0 < t < 12, therefore the domain of 4(pi)(t) is 0 < 4(pi)(t) < (48/25)(pi)(t), which is 6.031.
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Medicjug
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Can someone help me with part c?


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Medicjug
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Why does my way only give one of the solutions?


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studentwiz
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(Original post by Medicjug)
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Can someone help me with part c?


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Don't you just sub in T=18 k=0.0124 and t=70 then find B
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Medicjug
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(Original post by studentwiz)
Don't you just sub in T=18 k=0.0124 and t=70 then find B
I tried that it turns out you need to sub in t-60


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Medicjug
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Guys when you have -3sinx=cosx
How can we divide by cosx and do tanx=-1/3

I thought you can't divide by trig functions cause you lose the values where they equal 0????

Please help really confused


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Mr T Pities You
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(Original post by Medicjug)
Guys when you have -3sinx=cosx
How can we divide by cosx and do tanx=-1/3

I thought you can't divide by trig functions cause you lose the values where they equal 0????

Please help really confused


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This is only a problem when you would be dividing by zero. Cos and sin cannot both be zero for the same value of x so this isn't an issue here.
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Andy98
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(Original post by Medicjug)
Guys when you have -3sinx=cosx
How can we divide by cosx and do tanx=-1/3

I thought you can't divide by trig functions cause you lose the values where they equal 0????

Please help really confused


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What does the actual question say? I suspect x=/=0 is in there somewhere

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TeeEm
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useful material for the upcoming exams

http://www.thestudentroom.co.uk/show....php?t=3353445

http://www.thestudentroom.co.uk/show....php?t=3361867

http://www.thestudentroom.co.uk/show....php?t=3361905
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cerlohee
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(Original post by cerlohee)
Hi everyone, so I'm having trouble with this question: http://i.gyazo.com/90da8d80d402473cdbbd213855aedf55.png
I have worked out that b is 6, how do I then go onto work out A? Thanks

ALSO this question: http://i.gyazo.com/893eaaf9bd27c4b0a02a8512344a0a6c.png
I got a max value of 1.107 by making 100sinsq(theta-1.107)=0??
Anyone??:3
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Tow
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(Original post by Medicjug)
I tried that it turns out you need to sub in t-60


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Yeah it's (t-60) because the graph translates from 10 -> 70 and 60 -> 120

If you notice it's a difference of 60 so you write it as 10 < t-60 < 60

Please note: You DONT write it as t+60 which most people would automatically assume because if you look at my boundaries and rearrange it, doing t+60 would give -50 < t < 0
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s.c.a1
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which would you guys say are the hardest c3 papers that have come out so far (except last years) ive basically done all of the gold papers, now looking to fit in a few of the actual papers, which ones are worthwhile doing?
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samb1234
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(Original post by s.c.a1)
which would you guys say are the hardest c3 papers that have come out so far (except last years) ive basically done all of the gold papers, now looking to fit in a few of the actual papers, which ones are worthwhile doing?
Well in 2013 100 ums was like 64

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Krollo
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(Original post by s.c.a1)
which would you guys say are the hardest c3 papers that have come out so far (except last years) ive basically done all of the gold papers, now looking to fit in a few of the actual papers, which ones are worthwhile doing?
June 2013 is the notorious one. Otherwise take your pick from any after 2013 including IAL and R papers


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pearl_rose
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Anyone know a quick way of remembering all the identities? :]
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samb1234
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(Original post by pearl_rose)
Anyone know a quick way of remembering all the identities? :]
Firstly you don't really need to know a whole lot, as most are either on the formula sheet or can easily be derived from it eg sin2a isn't on there but sin(a+b) is so you can just do sin(a+a) to get the identity for sin2a. The only ones you really have to know are 1+tan^2 =sec^2 and 1+cot^2 =cosec^2

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randlemcmurphy
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(Original post by pearl_rose)
Anyone know a quick way of remembering all the identities? :]
(Original post by samb1234)
Firstly you don't really need to know a whole lot, as most are either on the formula sheet or can easily be derived from it eg sin2a isn't on there but sin(a+b) is so you can just do sin(a+a) to get the identity for sin2a. The only ones you really have to know are 1+tan^2 =sec^2 and 1+cot^2 =cosec^2

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For "1+tan^2 =sec^2 and 1+cot^2 =cosec^2" I would just recommend remembering sin2x+cos2x=1, and then altering that in the exam for the specific identity needed.
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samb1234
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(Original post by randlemcmurphy)
For "1+tan^2 =sec^2 and 1+cot^2 =cosec^2" I would just recommend remembering sin2x+cos2x=1, and then altering that in the exam for the specific identity needed.
Yes it is fairly easy to derive that one as well (just divide by sin^2 or cos^2) I just put that one as a lot of people don't realise that there is even an identity linking them so may not realise to do that in the exam

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Bustamove
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Can someone help me on question 5)b) ?
I don't understand how you can find the lower limit? help?
is it a recirpocal? and what is the best way to work out the range?
I usually draw a table but it takes too long

http://qualifications.pearson.com/co...-June-2014.pdf


Heres the markscheme
http://qualifications.pearson.com/co...-June-2014.pdf
Thanks
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