Edexcel FP2 June 2015 - Official Thread Watch

crashMATHS
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#41
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#41
(Original post by imyimy)
thanks! and something like this

http://www.examsolutions.net/a-level...estions/q6.gif

like if you had to find the area of the triangle and something else, in cartesian coord systems you'd just do 1/2 base x height or similar, but I'm not sure what you would do in polar. thanks!
You would do the same thing.

1. Work out the area of the sector.

2. Work out the lengths of the sides of the triangle. You do this by using the fact that  x=rcos\theta and  y = rsin\theta, because you have r and theta.

3. Use 1/2 base x height to calculate the area of the triangle

4. Area of R = Area of sector - Area of triangle




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imyimy
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#42
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(Original post by kingaaran)
You would do the same thing.

1. Work out the area of the sector.

2. Work out the lengths of the sides of the triangle. You do this by using the fact that  x=rcos\theta and  y = rsin\theta, because you have r and theta.

3. Use 1/2 base x height to calculate the area of the triangle

4. Area of R = Area of sector - Area of triangle




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Oh okay! I didn't realise you could do the x and y thing, thank you!
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username1259045
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#43
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for practice paper A, question 1, why have they continued to give values of theta >pi i thought
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darkdrifter10
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#44
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Hi guys in the june 2011 paper question 5c you had to keep use the method of w=x+iy . Was just wondering if there was a way of recognizing which method you had to use in a certain question of loci because i used the method to rearrange for z and got the answer wrong. thanks in advance
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Ryan965
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#45
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(Original post by darkdrifter10)
Hi guys in the june 2011 paper question 5c you had to keep use the method of w=x+iy . Was just wondering if there was a way of recognizing which method you had to use in a certain question of loci because i used the method to rearrange for z and got the answer wrong. thanks in advance
I think that when you are finding the point that it is transformed into you rearrange for z, while if you are finding what it is transformed from you swap them out for their real and imaginary parts. This is my weakest part of FP2 so I could be wrong but this is all I can think of for the two differences between the styles of the questions that require the methods
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crashMATHS
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#46
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#46
(Original post by darkdrifter10)
Hi guys in the june 2011 paper question 5c you had to keep use the method of w=x+iy . Was just wondering if there was a way of recognizing which method you had to use in a certain question of loci because i used the method to rearrange for z and got the answer wrong. thanks in advance
When you have z and you want w, you make z the subject and sub w= u+ iv into your equation (if you choose to do it using the component method).

If you have w and you want z, you keep w as your subject and sub z= x + iy into your equation (if you choose to do it using the component method).


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Ryan965
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#47
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Does anyone have any harder exam style questions or know where to find some since there doesn't seem to be any gold papers?
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bobabob
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#48
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#48
guys how to transfere y=-2x=5 from cartesian into the complex plain?

cheers!
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username1259045
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#49
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#49
(Original post by kingaaran)
When you have z and you want w, you make z the subject and sub w= u+ iv into your equation (if you choose to do it using the component method).

If you have w and you want z, you keep w as your subject and sub z= x + iy into your equation (if you choose to do it using the component method).


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if there's modulus are you always supposed to try and rearrange it, and if it doesn't work then sub x + iy?
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FN510
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#50
(Original post by mmms95)
if there's modulus are you always supposed to try and rearrange it, and if it doesn't work then sub x + iy?
Seems like it, but the transformations can get a bit dogdy. Also some of the answers in Ex.3H differ from the ones in the solution bank, like Q14b. I think the book is right
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username1259045
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#51
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(Original post by FN510)
Seems like it, but the transformations can get a bit dogdy. Also some of the answers in Ex.3H differ from the ones in the solution bank, like Q14b. I think the book is right
are you also doing the questions from the book to revise? or just past papers? there's a lot more questions for the years before 2009 (like about 13 questions per year)
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crashMATHS
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#52
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(Original post by mmms95)
if there's modulus are you always supposed to try and rearrange it, and if it doesn't work then sub x + iy?
Depends on what you're trying to achieve. If you are given two moduli, then you should sub x + iy in and apply Pythagoras, because it's well faster, but if not, then you can either use the component method or the perpendicular bisector method, depending on which you prefer.


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FN510
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#53
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(Original post by mmms95)
are you also doing the questions from the book to revise? or just past papers? there's a lot more questions for the years before 2009 (like about 13 questions per year)
If there's a topic I'm not too good with then I'll qickly work through the exercises, but otherwise I do exam qs from http://www.stgeorges-community.org.u...estions_V2.pdf + 2009 onwards + practice papers.
Are you ready??
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username1259045
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#54
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(Original post by FN510)
If there's a topic I'm not too good with then I'll qickly work through the exercises, but otherwise I do exam qs from http://www.stgeorges-community.org.u...estions_V2.pdf + 2009 onwards + practice papers.
Are you ready??

yeah im doing those questions aswell then im gonna move on to June 2009 + onwards past papers, are you finding the older years questions more lengthy btw/complicated (some) like especially when they ask you to draw a graph? (the trig ones)

(Original post by kingaaran)
Depends on what you're trying to achieve. If you are given two moduli, then you should sub x + iy in and apply Pythagoras, because it's well faster, but if not, then you can either use the component method or the perpendicular bisector method, depending on which you prefer.


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so in transformations there's basically two methods, but the component method always works? sorry i keep asking silly questions ahah i just get confused sometimes on what to do
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InOrbit
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(Original post by mmms95)
yeah im doing those questions aswell then im gonna move on to June 2009 + onwards past papers, are you finding the older years questions more lengthy btw/complicated (some) like especially when they ask you to draw a graph? (the trig ones)



so in transformations there's basically two methods, but the component method always works? sorry i keep asking silly questions ahah i just get confused sometimes on what to do
Correct, components will always give you a solution in any FP2 question. It is also very helpful if you need to state the Cartesian equation afterwards.

Mod(z) substitution should only be used when the question explicitly tells you some information about the transformation, such as: it's a circle, it's a line or it lies on the real axis.
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FN510
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(Original post by mmms95)
yeah im doing those questions aswell then im gonna move on to June 2009 + onwards past papers, are you finding the older years questions more lengthy btw/complicated (some) like especially when they ask you to draw a graph? (the trig ones)
For the graphs, I just use the table mode on my calc to help me get the shape
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FN510
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#57
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#57
(Original post by Alex:)
Mod(z) substitution should only be used when the question explicitly tells you some information about the transformation, such as: it's a circle, it's a line or it lies on the real axis.
It seems like you can rearrange to get different loci?? Is that why they specifically state the type?
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username1259045
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#58
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http://qualifications.pearson.com/co..._June_2005.pdf Q1b why do they times by 1/2 in the markscheme?
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username1259045
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#59
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#59
(Original post by FN510)
For the graphs, I just use the table mode on my calc to help me get the shape
same! is that the only method though?
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Mjmuk
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#60
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#60
(Original post by mmms95)
for practice paper A, question 1, why have they continued to give values of theta >pi i thought
What paper are you referring to?
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