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

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I'm more concerned about my IGCSE Double Award Science grades. The Biology exam went pretty bad. But I think I can do well in my Physics and Chemistry, so it'll help bring up my grades. :smile:

Reply 21

m8nmina0h4

themariii

our shiny A*'s.
-stares-

:biggrin:

Not for me. Anybody got any thoughts on my post (#8) was hoping for some opinions on what I did for the last question.

Reply 22

ydhdfhfghaghgahgfh

I'm sure if you do well in Paper 4H, you can get an A*. I mean, you need about 170/200 in total to get one. You can do it!

Reply 23

m8nmina0h4

digitalsubstance

I'm sure if you do well in Paper 4H, you can get an A*. I mean, you need about 170/200 in total to get one. You can do it!

But why do you think I got that math error when doing inversine sine?

Reply 24

rc18

KnightRider

But why do you think I got that math error when doing inversine sine?

I think its just impossible. I you put any number after inverse sine it comes up with maths error.

Reply 25

ydhdfhfghaghgahgfh

You can only use the inverse of sin with numbers less than or equal to 1.

Reply 26

m8nmina0h4

digitalsubstance

You can only use the inverse of sin with numbers less than or equal to 1.

So how was I meant to work out the angle with sine rule :s-smilie:

You'd need to do inverse sine at some point.. :s-smilie:

This probably means I didn't even get any method marks :frown:

Reply 27

ydhdfhfghaghgahgfh

I think you use the cosine rule:

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) = 16.3 degrees (3 significant figures)

Reply 28

m8nmina0h4

digitalsubstance

I think you use the cosine rule:

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) = 16.3 degrees (3 significant figures)

Okay in that case I got 0 probably on the whole question.

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

14 + 2 = 16.

:biggrin:

Reply 31

StudentInDistress

I messed up badly in the gradient question, lost 8 marks there and for some reason the proportionality question confused me, like was I supposed to convert it to km or m?
Anyways I missed the whole differentiation/gradient lesson in school since I was sick and now I'm worried about paper 4H :frown:

I really wish someone would be able to explain how the gradient question worked.

Reply 32

SH2007

wasnt a* last year 79? i dont think its usually as high as 85 is it?

Reply 33

ydhdfhfghaghgahgfh

StudentInDistress

I really wish someone would be able to explain how the gradient question worked.

Basically.

Remember this:

x^n --> nx^n-1.

You multiply by the power, and then subtract one off the power.

(dy/dx) is the derivative (rate of change) of y with respect to x. In basic terms, (dy/dx) is the gradient. The d stands for the Greek letter, delta, which means change. When differentiating, remember that whole numbers differentiate to zero, and anything to the power of zero, is 1. You also get things called turning points, which are basically points on a graph where the gradient is equal to zero. To determine whether a turning point is a maximum or minimum, differentiate twice to get (d^2y/d^2x), and then substitute in your x value. If you get a positive value, then it is a minimum, and if you get a negative value, then it is a maximum. If you get zero, then it is a point of inflection. o_O

For example, 3x^2 differentiates to 6x, and d^2y/d^2x = 6.

Also:

velocity = ds/dt
acceleration = dv/dt

The way to think about it, is to get velocity, you differentiate once, and to get acceleration, you differentiate twice. Much like when working out maxima and minima. :smile:

Edit: Have a look at this - http://www.mathsrevision.net/alevel/pages.php?page=23, http://www.mathsrevision.net/alevel/pages.php?page=9, http://www.mathsrevision.net/alevel/pages.php?page=45 and http://www.mathsrevision.net/alevel/pages.php?page=43.

Reply 34

m8nmina0h4

StudentInDistress

I really wish someone would be able to explain how the gradient question worked.

**** were you meant to convert the units in the proportion question? I didn't see that! :O

Reply 35

ydhdfhfghaghgahgfh

^^ To be honest, you probably didn't understand any of that, and it is understandable. It is part of calculus, which is part of AS Maths, and really needs a teacher or someone to go through it thoroughly with you.

^ What, we needed to convert the units? I didn't see that. O_O

Did everybody get your constant (k) as 3.6 though?