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How did you find this year's C4 (EDEXCEL)

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Original post by seneethy
How did u do the vector question ? Where we need to find the shortest distance


Shortest dist = perpendicular to the line L. You have to use simple trig to get the length as its a right angle triangle. Hope that makes sense.
Reply 81
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math42
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Original post by seneethy
How did u do the vector question ? Where we need to find the shortest distance


I'm bad with vectors and someone may say I'm wrong but

I did ABsintheta, where theta is the angle you worked out in the previous part
I drew a diagram with a right angled triangle, the perp. from l1 going to B, the hypotenuse being AB, and it followed from that seemingly
I could actally do 8b....but not part a so i couldnt get the actual answer because you needed part a to work it out :c
Original post by TeeEm
My first student reported...
he claims the paper was ok (not easy nor hard)
(this is from 295 in year 12, 100% in C3)


I was expecting it to resemble some sort of monster from the deep but I actually found it fine and I got 255 last year.
Reply 84
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MPH1997
4
Anyone get 2-(1/ln3) for x coordinate of Q


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Original post by seneethy
How to do the vector question ? Where we need to find the shortest distance


It's the perpendicular distance from B to line l1, using the angle you calculated and the right angled triangle.
Reply 86
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TeeEm
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Original post by emu_neutrino
I was expecting it to resemble some sort of monster from the deep but I actually found it fine and I got 255 last year.


all relative...
Reply 87
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math42
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Original post by MPH1997
Anyone get 2-(1/ln3) for x coordinate of Q


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Yeah
Then 13pi/ln3 for the volume
I find it amusing that my teacher only taught a few members of the class how to use A^x rule the other day... she completely forgot to teach us during the year as she thought it was irrelevant... lol
Reply 89
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Skitee
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Original post by k4l397
I thought the paper was decent. The questions were all pretty standard imo which was a nice change.

Last one was quite tricky though, can anyone remember what they got for that? Heard a range of answers from other people in my class so have no clue if I got it right or not.


Agreed - I really thought it was an easy paper, everything which came up had come up in previous years, nothing there was particularly challenging at all. Really surprised at the poll, most people I talked to thought it was quite standard, vectors was an easy question and rates of change didn't even turn up!

13pi/ln(3) is the result almost everyone in my college got. Pretty sure it's right
Original post by seneethy
Is it correct I was also wondering about it ,but since they haven't mentioned any thing saying it's perpendicular we cannot use that I think we have to introduce a new point on l1 and if we say it's C. We have to find AC and also find lamnda and equate it to the AC that's what I did not sure though


the shortest distance from a point to a line is the perpendicular distance between the point and the line.
Reply 91
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seneethy
Original post by phoenixsilver
It's the perpendicular distance from B to line l1, using the angle you calculated and the right angled triangle.


They haven't mention anything about that being perpendicular know can we assume
Trapezium rule didn't come up either!


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Original post by Skitee
Agreed - I really thought it was an easy paper, everything which came up had come up in previous years, nothing there was particularly challenging at all. Really surprised at the poll, most people I talked to thought it was quite standard, vectors was an easy question and rates of change didn't even turn up!

13pi/ln(3) is the result almost everyone in my college got. Pretty sure it's right


I think I got that :biggrin: People at my college were a bit mixed but I think most thought it was standard even if they found it hard.
Reply 94
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Skitee
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Original post by seneethy
They haven't mention anything about that being perpendicular know can we assume


Because, logically, the closest distance is going to be the perpendicular distance. Of course, this is unless you can think of any example of the closest distance from a point to a line not being perpendicular to the line?
Original post by seneethy
They haven't mention anything about that being perpendicular know can we assume


Because the shortest distance is perpendicular.
Original post by 1 8 13 20 42
I did the same but I probably missed something...I have a tendency to lose objectivity with questions and think about them in terms of the perception I've already gained, if that makes sense, and even if something is blatantly dumb, unless it's as simple as a sign error, I'll miss it. Hopefully I had close to 100 in C3 so there is a fair bit of leeway, which I may need
Yeah last year's paper was probably the hardest since the spec change (there were a couple tricky old ones). I felt this paper was also a little bit more skewed but overall more consistent I suppose; its last questions were certainly more forgiving - although the volume of revolution was slightly cheeky


I have no leeway haha I need the 90 UMS as I scraped 90 in C3 last year.
I did the vectors both ways. I did one way with minimising lamda and the normal quick way. Both got the desired answer of 7.46 or whatever it was.


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Oh well there goes my A*. The last question was the work of satan himself. How was I supposed to know how to integrate 3^x I never came across it in the textbook and I did every question in it. So much hard work this year all in vain.
Reply 99
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math42
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Original post by physicsmaths
I did the vectors both ways. I did one way with minimising lamda and the normal quick way. Both got the desired answer of 7.46 or whatever it was.


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I had 7.46 woo, never sure about vectors
What exactly does the first method entail?

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