MHB Help with O Level Math 4024 Exam Questions

  • Thread starter Thread starter leylamew
  • Start date Start date
  • Tags Tags
    Levels
AI Thread Summary
A student preparing for the Cambridge O Level Math 4024 exam is struggling with specific questions from a 2010 past paper, particularly questions 9bi, 10, 11, and 12. They express confusion about finding the length MN in a geometric problem involving congruent triangles and relationships between segments. After some discussion, it is clarified that MN equals 2x, based on the congruence of triangles and the measurements taken from the diagram. The conversation also touches on calculating the area of a circular sector and subtracting the area of a triangle to solve the problem. Overall, the thread highlights the collaborative effort to understand and solve complex math problems.
leylamew
Messages
3
Reaction score
0
Hi, I'm leylamew.
So, I'm in the Cambridge University O Level board and I'm studying for my examinations, which will be in May. I'm taking the Math 4024 paper.
I was solving the past paper for 2010 and I hit a roadblock. (Shake)
Here's the link. http://papers.xtremepapers.com/CIE/Cambridge%20International%20O%20Level/Mathematics%20D%20(Calculator%20Version)%20(4024)/4024_s10_qp_21.pdf

It's questions 9bi, 10, 11 and 12 that are bothering me greatly.
Help? :D
 
Mathematics news on Phys.org
leylamew said:
Hi, I'm leylamew.
So, I'm in the Cambridge University O Level board and I'm studying for my examinations, which will be in May. I'm taking the Math 4024 paper.
I was solving the past paper for 2010 and I hit a roadblock. (Shake)
Here's the link. http://papers.xtremepapers.com/CIE/Cambridge%20International%20O%20Level/Mathematics%20D%20(Calculator%20Version)%20(4024)/4024_s10_qp_21.pdf

It's questions 9bi, 10, 11 and 12 that are bothering me greatly.
Help? :D

You are supposed to at least show some effort and tell us where are you stuck ?
 
ZaidAlyafey said:
You are supposed to at least show some effort and tell us where are you stuck ?

I'd upload the sheet where I've scribbled the logic, but I don;t have a scanner.
Here's my thinking process:
OB=OA=OP=8 cm and as OQ is x cm, MN should be...something. But I can't understand for the life of me, how to find MN. I don't understand what I'm supposed to do with the x there.

- - - Updated - - -

leylamew said:
I'd upload the sheet where I've scribbled the logic, but I don;t have a scanner.
Here's my thinking process:
OB=OA=OP=8 cm and as OQ is x cm, MN should be...something. But I can't understand for the life of me, how to find MN. I don't understand what I'm supposed to do with the x there.

And, I don't understand what the questions are asking of me in the others.
 
leylamew said:
I'd upload the sheet where I've scribbled the logic, but I don;t have a scanner.
Here's my thinking process:
OB=OA=OP=8 cm and as OQ is x cm, MN should be...something. But I can't understand for the life of me, how to find MN. I don't understand what I'm supposed to do with the x there.

- - - Updated - - -
And, I don't understand what the questions are asking of me in the others.

All right, so I put my ruler to use and hoping that the diagram was to scale, I measured MQ and OQ. They're the same, so I safely assumed that MQ is x and so, therefore, MN is 2x, as MQ is 1/2MN. Did I do it right?
 
leylamew said:
All right, so I put my ruler to use and hoping that the diagram was to scale, I measured MQ and OQ. They're the same, so I safely assumed that MQ is x and so, therefore, MN is 2x, as MQ is 1/2MN. Did I do it right?

Yes, as triangles $MOQ$ and $NOQ$ are congruent, and are right isosceles triangles, we know that:

$$\overline{MQ}=x$$

$$\overline{QN}=x$$

and so adding, we have:

$$\overline{MQ}+\overline{QN}=2x$$

And we know that $$\overline{MQ}+\overline{QN}=\overline{MN}$$, hence:

$$\overline{MN}=2x$$

Now, for the next part of the problem, find the total area of the cross-section using the formula for the area of a circular sector (or simply from the fact that it is a quarter circle) and then subtract away the area of triangle $MON$. What do you find?
 
Last edited:
MarkFL said:
$$\bar{MQ}=x$$
@MarkFL: Just a comment about the LaTeX coding: \overline{AB} gives \overline{AB}. I think that looks like a better operation here than \bar.

-Dan
 
Last edited by a moderator:
Thank you, that does look better! (Happy)
 
MarkFL said:
...
Now, for the next part of the problem, find the total area of the cross-section using the formula for the area of a circular sector (or simply from the fact that it is a quarter circle) and then subtract away the area of triangle $MON$. What do you find?

Hints:

The area $A_S$ of a circular sector is:

$$A_S=\frac{1}{2}r^2\theta$$

and you know $r$ and $\theta$.

The area $A_T$ of a triangle is:

$$A_T=\frac{1}{2}bh$$

and you know the base $b$ and the height $h$ in terms of $x$. So you now need to compute:

$$A=A_S-A_T=?$$
 
Back
Top