# P5 OCR 21st June

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#1
how was it, i found it quite nice really. very similar in difficulty to previous years. should get an A hopefully.
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15 years ago
#2
yup very nice, that reduction formula for sin^n(x) was in the text book and i read it yesterday!

i didn't have enough time to finish the last question, I got lambda = 0 and mew = -1/6

surface area = 2pi(1 - e^-1)

can't think of much else, oh and i got one the the roots of the equation wrong, the alpha^4 + beta ^4 .... one. Oh well.
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15 years ago
#3
(Original post by jonas123)
yup very nice, that reduction formula for sin^n(x) was in the text book and i read it yesterday!

i didn't have enough time to finish the last question, I got lambda = 0 and mew = -1/6

surface area = 2pi(1 - e^-1)

can't think of much else, oh and i got one the the roots of the equation wrong, the alpha^4 + beta ^4 .... one. Oh well.
ditto, it was an easy paper just really long
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15 years ago
#4
sigma alpha^2 = 10

sigma alpha^3 = -3

sigma alpha^4 = 50

the very last question y=(pi/18)sin2x -(1/6)xsin3x

the length of the arc was 0.5e-0.5e^-1

the first question x=1.2 y=2.62

most of the other questions were show that.

And i think INT sin^5x between (pi/3)and 0 was 53/480
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15 years ago
#5
for the reduction formula one, i kinda got screwed on the second part, as i couldn't put my numbers into fractions lol!!!
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15 years ago
#6
(Original post by PhilC)
sigma alpha^2 = 10

sigma alpha^3 = -3

sigma alpha^4 = 50

the very last question y=(pi/18)sin2x -(1/6)xsin3x

the length of the arc was 0.5e-0.5e^-1

the first question x=1.2 y=2.62

most of the other questions were show that.

And i think INT sin^5x between (pi/3)and 0 was 53/480

i thought the complementary function for the last question was ACos3X + BSin3X???

A=(pi/6), B=1/18
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15 years ago
#7
Actually im not sure about the very last bit where you had to solve the defferential eqation.

did it say dy/dx=0 when x=pi/3

or did it say dy/dx=0 at some point (pi/3, y)
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#8
all those answers agree with mine from memory. i didn't get sigma^2 of the polynomila root question but i've since checked my answer and its definitely -3. fairly straight forward overall, took the 1:20 time almost exactly.
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15 years ago
#9
yes the complemantary function was Acos3x + bcin3x

Then you had to solve for the condtions
i think i may have misread the conditions though and made an error
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15 years ago
#10
(Original post by PhilC)
Actually im not sure about the very last bit where you had to solve the defferential eqation.

did it say dy/dx=0 when x=pi/3

or did it say dy/dx=0 at some point (pi/3, y)

i thought it said st. point at ((pi/6),0) (i.e dy/dx=0 when x=0 y=0)
0
15 years ago
#11
Well

y=Acos3x+Bsin3x-(1/6)xcos3x

dy/dx=3Bcos3x-3Asin3x-(1/6)cos3x+(1/2)xsinx

x=pi/3
y=0
dy/dx=0

so
0=0-3A-0+(pi/6)
so A=(pi/18)

and from y equtaion
y=0+b-o
B=0

So
y=(pi/18)cos3x-(1/6)xcos3x

i think
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15 years ago
#12
x=pi/6
not
pi/3

sorry
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15 years ago
#13
another typo,

-(1/2)xsin3x

not

-(1/2)xsinx
0
#14
"So
y=(pi/18)cos3x-(1/6)xcos3x"

agree completely there 0
15 years ago
#15
Is that what you got then?

i actually got -(pi/180.....
so a minus sign in the wrong place, but should lose only one mark for that.

I think everything else was pretty much alright for me, but will the examiner be able to read my handwritting is the more important question.
0
#16
actually, i cant remember now. i'll rework the question in after lunch and double check but it looked very similar to y=(pi/18)cos3x-(1/6)xcos3x.
i think i took a factor of 1/18 out tho. but thats makes no difference
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15 years ago
#17
all the prove it questions were relatively simple, i thought i wouldn't get them but they just popped out in the end.
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15 years ago
#18
Yea, they were ok, chain rule for the d/dx sinh^-1 questions,

Cosh^-1x=ln(x=root(xx-1)) or something, done that before.

that was about it for them wasnt it?
The newton-rapshon eon just set f(x)=1+2/x -lnx
and show f(4) is bigger than 0 and f(5) is less than 0.

4.32 was the root for that iteration i think.

I think that was about it really not too much, when i opened the question paper it looked a lot harder than it was i think, quite a lot of volume, but nothing too testing i don't think.

BTW Where and what are you doing at univeristy.
BTW.2 Ainsworth, you have the same birthday as me, and you doing the same A Levels, just thought that was a little bit of a coincidence.
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#19
really? 15th march 86.
currently i have an offer to study engineering at cambridge, girton college starting in october. where u going to uni?
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15 years ago
#20
Sidney Sussex, for Maths, but im not sure ill make it.
Ive done pretty poor in these exams, but if i put in a good performance in S2 i should get an A in further maths.

If of course i can have
P1,P2,P3,P4,D1 and S1 in maths
and P5,P6,M1,M2,M3 and S2 in Further maths but im not sure if thats allowed.

Then of course there is STEP, but ive done a lot of prctice for that so hopefully i should be ok.
0
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