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Edexcel IGCSE Mathematics: 4400 (Paper 3H) - May 15th 2008

How did everyone find it yesterday? I'm kicking myself because I made one stupid mistake on the kite question where I did (c^2/a^2) instead of (c^2 - a^2). Oh well.

What do you think will come up in Paper 4H?

If people want clarification on some answers, here are some. Feel free to share different methods and more answers.

In the question with (x + 36) degrees, x = 96.

Since, (x + 36) + 0.5x (angle at circumference is half angle at the centre) = 180.
1.5x + 36 = 180
1.5x = 180-36 = 144
x = 144/1.5
x = 96

For the question with the two squares and hexagon, n = 12. Since, the interior angle of the square was 90, and the interior angle of the hexagon was 120. Therefore, 360 - 210 = 150, which is the sum of an interior angle of the n sided shape. Using ((n-2) * 180)/n = 150, you solve it to get n = 12.

There have been mixed opinions on the gradient question, where you had to draw a tangent. I myself got an answer of 8 (4/0.5).

The final question was fairly straightforward, even though it seemed complicated. You had to split the kite into two triangles. Using Pythagoras (2^2 + 2^2) = h^2, you get the hypotenuse as root(8) or 2(root)2. You can then either use 0.5(ab)SinC after using cosine rule, or you can split the larger triangle into two smaller right angled triangles, and get the height as 7(root)2 or root(98). Then using 0.5(base * height), and multiplying that by two (as there are two triangles), and adding on the smaller triangle's area (which was 2), you get an answer that is rounded to 16cm^2.

Edit: The Cosine rule way of working this out is below:

cosA = (b^2 + c^2 - a^2)/2bc

cosA = (10^2 + 10^2 - (root(8))^2)/(2 x 10 x 10)
cosA = 0.96
A = cos^-1(0.96)

0.5(100) * sin(cos^-1(0.96)) = 14.

14 + 2 = 16.

In the proportion question, the constant (k) = 3.6.
The formula was therefore, d = 3.6*root(h).

In the probability question, where you needed to give the probability of getting a score that totalled 43, the answer was (4/81).

21 --> 22 = (1/81)
22 --> 21 = (1/81)
20 --> 23 = (1/81)
23 --> 20 = (1/81)

Therefore the total is (4/81).

Many people have been asking what the A* boundary will be, and honestly we do not know, but since the paper was not very challenging, we think that it will be somewhere between 85 and 88 per cent.

Reply 1

ydhdfhfghaghgahgfh

OP

For Loci, do we only need to know how to do the angle bisector thing?

yup. we do :smile:

OP

I hope we get some tasty functions in 4H. Haha.

Reply 4

[m a a r i.]

HAHAHA
i hope we have simultaneous equations.
i love em'
:biggrin:

Reply 5

ydhdfhfghaghgahgfh

OP

Ah, I love simultaneous equations. Especially when they give you something like the equation of a circle, x^2 + y^2, and then ask you to substitute in. <3

Reply 6

[m a a r i.]

YEAH YEAH!!!
and of course i love the adding and subtracting dividing and multiplying at the first question HAHA

Reply 7

m8nmina0h4

15

digitalsubstance

How did everyone find it yesterday? I'm kicking myself because I made one stupid mistake on the kite question where I did (c^2/a^2) instead of (c^2 - a^2). Oh well.

What do you think will come up in Paper 4H?

If people want clarification on some answers, here are some. Feel free to share different methods and more answers.

In the question with (x + 36) degrees, x = 96.

Since, (x + 36) + 0.5x (angle at circumference is half angle at the centre) = 180. If you solve that you get x = 96.

For the question with the two squares and hexagon, n = 12. Since, the interior angle of the square was 90, and the interior angle of the hexagon was 120. Therefore, 360 - 210 = 150, which is the sum of an interior angle of the n sided shape. Using ((n-2) * 180)/n = 150, you solve it to get n = 12.

There have been mixed opinions on the gradient question, where you had to draw a tangent. I myself got an answer of 8 (4/0.5).

The final question was fairly straightforward, even though it seemed complicated. You had to split the kite into two triangles. Using Pythagoras (2^2 + 2^2) = h^2, you get the hypotenuse as root(8) or 2(root)2. You can then either use 0.5(ab)SinC after using cosine rule, or you can split the larger triangle into two smaller right angled triangles, and get the height as 7(root)2 or root(98). Then using 0.5(base * height), and multiplying that by two (as there are two triangles), and adding on the smaller triangle's area (which was 2), you get an answer that is rounded to 16cm^2.

I'm really annoyed at myself for that exam, it was probably one of the easiest paper 3Hs I've seen and I lost my chance of getting an A*. Although I think I did fairly well in the first questions, I really messed up the last 2. For the penultimate question I literally only attempted the gradient question, and I can't remember what I got for that and it's probably wrong, so at worst it's -8 marks! Then the last one, I spent ages on it, and wasted so much time when it was actually quite simple!

For the bigger triangle I was trying to use the cosine rule as I had to sides and wanted to find the angle enclosed by them, but I kept getting a Maths error on the final step, as I had something line SinC=9 and when I tried do use the inverse sin to get the angle I got that error!

For the smaller triangle I think I used pythogoras but I don't really remember any of the figures, I think I got 1.8 somewhere or something like that, but not sure :s-smilie:

Anyway I'm just really pissed off as I think I've blown my chances of an A* and probably lost literally 14 marks on the last 2 questions, and assuming I got everything else right (which is possible unless I made stupid mistakes in other questions) that is 86, but I'm guessing they'll raise the grade boundaries this year because of the easy paper!

Any thoughts on above.. really would love some reassurance lol!

:smile:

Reply 8

rc18

digitalsubstance

In the question with (x + 36) degrees, x = 96. .

yeah i got that too

digitalsubstance

For the question with the two squares and hexagon, n = 12. .

got that too :smile:

for that last one with the kite did you have to write cm^2? I dont think i did damnit!!

what did you get for the probability one, where it had to add up to 43? I got 8/81 :s-smilie:

Reply 9

ydhdfhfghaghgahgfh

OP

I love calculus as well. Although they teach it really strangely at my school, when determining whether a turning point is maxima or minima. I always use the second derivative, by differentiating (dy/dx) again to get (d^2y/d^x), and then substituting x into it again. +ve = minima -ve = maxima. However, they tell us to draw this weird x value table, with sketches. o_O

Reply 10

[m a a r i.]

i need to CHECK and CHECK for 4H's paper.
and continue doing past papers for maths.
haha
dont lose hope :smile:

we still have the chances to get the A*'s

Reply 11

ydhdfhfghaghgahgfh

OP

The probability question was (4/81).

As the ways to get a total of 43 are:

21 --> 22 = (1/81)
22 --> 21 = (1/81)
23 --> 20 = (1/81)
20 --> 23 = (1/81)

Reply 12

Raminder1992

you know in the paper do you get full marks for a question without working? because in the tiles question i got 12 but i found it out by drawing a diagram!! some people say in GCSE you get full marks but im not sure, does anyone know? and what did any1 get in the probability question when they added up to 43! also the gradient (1st part on the second from last Q)?? thanks!!
In the second paper thell be calculus nd histograms but probally no functions! simultanious equations aswell! if they give us one with squares thats good coz itll be like 6 easy marks!! also theres guna be algebra cos there wernt much in it yes2day!!

Reply 13

ydhdfhfghaghgahgfh

OP

No, our school received a letter from Edexcel saying that no marks will be awarded if a student gives a correct answer without any working. :frown:

Reply 14

m8nmina0h4

15

Raminder1992

you know in the paper do you get full marks for a question without working? because in the tiles question i got 12 but i found it out by drawing a diagram!! some people say in GCSE you get full marks but im not sure, does anyone know? and what did any1 get in the probability question when they added up to 43! also the gradient (1st part on the second from last Q)?? thanks!!
In the second paper thell be calculus nd histograms but probally no functions! simultanious equations aswell! if they give us one with squares thats good coz itll be like 6 easy marks!! also theres guna be algebra cos there wernt much in it yes2day!!

No I don't think you'd get 6 marks for just drawing a shape. You'll probably get 1 or 2 but don't think they'll give you all 6.

I think functions will come up in 4H, as well as vectors too.

Reply 15

Raminder1992

wnt u get any for drawing a diagram lol thats pushing it!! i know quite a few people which did exactly the same as me!! lets hope in the 4H we dnt make any mistakes!! vectors will come up yehh well just have to wait and see! 1 or 2 marks is better than 0.

Reply 16

ydhdfhfghaghgahgfh

OP

Oh, if you did some working, then you might get 1. But drawing a diagram isn't the correct way of proving that n = 12. They wanted the algebraic method as well. D: