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# Maths Ocr 2016 C1

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1. (Original post by blinin7)
is a stretch parallel to x axis of scale factor 2
THE SAME AS
a stretch parallel to Y axis of 1/2?
No, not really. take the point (2,2) for instance:
a stretch parallel to the x-axis scale factor 2 would transform it to (4,2), f(1/2x)
a stretch parallel to Y-axis scale factor 1/2 would transform it to (2,1), 1/2f(x)
2. (Original post by dsouza22neeson)
Sorry i still don't understand cos i cant remember how the diagram looked, was 0,0 inside the circle?
I'll draw it out for you and then reply with a picture, and i'll try to explain that
3. (Original post by FluffyCommie)
No, not really. take the point (2,2) for instance:
a stretch parallel to the x-axis scale factor 2 would transform it to (4,2), f(1/2x)
a stretch parallel to Y-axis scale factor 1/2 would transform it to (2,1), 1/2f(x)

Surely they have the same gradient though, which is was is important when stretching? - or is that irrelevant?

Trying to see if I can get anything out of those 3 marks. Was 50/50 over saying 1/2 to Y or 2 to X and went for X instead...
4. (Original post by ellie98)
Hi everyone,
I personally found this paper very difficult and believe it was the hardest paper I have ever done out of all the spec questions and the Solomon papers too. Having looked through the unofficial markschemes I think I have lost about 20 marks. In my mock I got 69/72. Reassuringly, my maths teacher just sent round this email to my year:
Attachment 533987
That's really reassuring to know thank you! Grade boundaries are relative to how the whole population does so the top 80% get A etc. And it sounds like everyone found it really hard so I'm sure they'll reflect that. Just don't let it knock your confidence for C2! Also C1 in the past has had very high grade boundaries with a lot of people getting full marks whereas the grade boundaries for C2 are more normal so they might just have made C1 loads harder and kept C2 the same
5. (Original post by FluffyCommie)
I'll draw it out for you and then reply with a picture, and i'll try to explain that
https://gyazo.com/1b6eeb91cbb17834cd93d03e3222afd0
6. well I'm utterly ****ed.
7. (Original post by 09brewh)
well I'm utterly ****ed.
Trust me you have probably done better than you have thought mate. I have been feeling depressed the whole day after that exam but lets just pray for an easier c2 and s2 and lower grade boundaries. Don't let one exam dishearten you mate.
8. Any ideas what the grade boundaries will be?

I got about 55 on that, which is terrible performance (~75%) compared to the 90ish%'s I was getting whilst doing past papers. Not sure if I just choked under pressure or if the exam was generally harder...
9. (Original post by dsouza22neeson)
Sorry i still don't understand cos i cant remember how the diagram looked, was 0,0 inside the circle?
As you can see from this terrible drawn diagram (Correct me if it's wrong):

The question asks you to find the range of values for r. I have labelled r in the diagram, and as it is labelled, would be the maximum radius for the smaller circle. Now, you know L (which i've labelled as the WHOLE dashed line) as the diameter, previously worked out as sqrt(45)
but to find the maximum value of r, we need to take the distance from the centre at (4,3) to the centre (0,0)
Using: L= ((x2-x1)^2 + (y2-y1)^2)^1/2 you calculate that L=5
Therefore, r = sqrt(45) - 5
and since r cannot be 0, we get the range 0<r<sqrt(45)-5
Attached Images

10. Where did you get y=2x-20 from. NOOO why did I get y=2x-5??
11. (Original post by DanMcGrathKB)
Shut up max you're not road, posh boy Attachment 533855
its a joke mate haha
12. (Original post by Dmitry_Mednov)
It is wrong as if you use k as -5 or -6 it will not intersect the curve, I checked it at the end.
Actually, I think I was right as I tested it and sketched a graph... And also that's what they got on the unofficial mark scheme. https://docs.google.com/document/d/1...nw/mobilebasic
13. well, I just wasted 5 minutes of my life xD
14. Hi, here is a link to an unofficial Mark scheme for today's paper! https://docs.google.com/document/d/1...nw/mobilebasic
15. Someone help me for the tangent question...
I worked out the coordinate of A which I got to be (10,0)
Then I used y1-y2/x1-x2 to get a gradient of -0.5. So the gradient of the tangent was 2.
Then use the Centre (4,3)
y-3=2(x-4)
y-3=2x-8
y=2x-5
WHAT DID I DO WRONG!
16. (Original post by Logic4Life)
Someone help me for the tangent question...
I worked out the coordinate of A which I got to be (10,0)
Then I used y1-y2/x1-x2 to get a gradient of -0.5. So the gradient of the tangent was 2.
Then use the Centre (4,3)
y-3=2(x-4)
y-3=2x-8
y=2x-5
WHAT DID I DO WRONG!
You don't sub in the centre you sub in the coordinates at that point :/
17. (Original post by blinin7)

Surely they have the same gradient though, which is was is important when stretching? - or is that irrelevant?

Trying to see if I can get anything out of those 3 marks. Was 50/50 over saying 1/2 to Y or 2 to X and went for X instead...
What's more important with stretches, in C1 specifically, is just the transformation of specific points on the graph, as far as I know. So the gradient is irrelevant.

I'd also like to add that
18. (Original post by 09brewh)
You don't sub in the centre you sub in the coordinates at that point :/
But I subbed in (10 0) for the second tangent on the next question!
19. (Original post by Luketidley)
Circles also do not come up on C1, geometry of a circle is a topic on c2! The topics for C1 are;
Surds and Indices,
Quadratic functions, equations, graphs and transformations,
Coordinate geometry and straight lines,
Polynomials and the binomial expansion,
and Differentiation!

These are on my course and I'm doing WJEC.
This is for OCR
20. (Original post by Logic4Life)
But I subbed in (10 0) for the second tangent on the next question!
For part 1
Y-y1=m(x-X11)
Y-0=2(x-10)
Y= 2x - 20

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