AQA A2 Mathematics MPC4 Core 4 - 9th June 2015 [Discussion &amp; unofficial markscheme]

OP

Original post by geeky_penguin

I am really struggling with the trigonometry in core 4. Can anyone suggest any revision materials from it? And is it a big topic in the exam?

Have you checked out some of the resources on the first post of the thread?

I use the CGP A2 Mathematics revision guide and it's great for summary questions for particular topics. Also try physicsandmathstutor for topic by topic questions - it'll allow you to do as many past paper questions for a given topic as possible.

It's always going to come up in the exam. Whether or not it is allocated a "big" number of marks is entirely dependent on the mood of the examiner :L

Posted from TSR Mobile

Reply 342

OP

Original post by Tiwa

Yeah. I should've specified that. 😄

Ah, what was the hardest question for you? Personally the painting one I thought was tricky.

Posted from TSR Mobile

Reply 343

username1763825

Original post by CD223

Ah, what was the hardest question for you? Personally the painting one I thought was tricky.

Posted from TSR Mobile

The painting one was sly, just highlights the new style of papers from AQA.
Not many people realised you need the value of the first painting in 1991 too.

Posted from TSR Mobile

Reply 344

username1763825

Original post by geeky_penguin

I am really struggling with the trigonometry in core 4. Can anyone suggest any revision materials from it? And is it a big topic in the exam?

I found the trig in c4 tricky too especially the R-Alpha method. I found a great site that really helped me understand the topic.

www.mathematicsi.com/r-alpha-method/
The have step by step examples on other topics too.

Posted from TSR Mobile

Reply 345

username1854637

Original post by CD223

Have you checked out some of the resources on the first post of the thread?

I use the CGP A2 Mathematics revision guide and it's great for summary questions for particular topics. Also try physicsandmathstutor for topic by topic questions - it'll allow you to do as many past paper questions for a given topic as possible.

It's always going to come up in the exam. Whether or not it is allocated a "big" number of marks is entirely dependent on the mood of the examiner :L

Posted from TSR Mobile

Thank you so much! I normally use the heinemann text book for the questions but it just confuses me in the trig topic. I will definitely take a look at the CGP book!

Reply 346

username1854637

Original post by Waz96

I found the trig in c4 tricky too especially the R-Alpha method. I found a great site that really helped me understand the topic.

www.mathematicsi.com/r-alpha-method/
The have step by step examples on other topics too.

Posted from TSR Mobile

I didn't know about that site! It's really useful from what I have seen so far. thank you!

Reply 347

username1763825

Original post by geeky_penguin

I didn't know about that site! It's really useful from what I have seen so far. thank you!

No problem :smile:

Reply 348

madmenace

8

Hi; you know the paining one? I'm not 100% sure why you add on 10 years when solving for t.... also why does it roll into 2018 beacuse it's 2017.something

Reply 349

OP

Original post by Waz96

The painting one was sly, just highlights the new style of papers from AQA.
Not many people realised you need the value of the first painting in 1991 too.

Posted from TSR Mobile

I agree. That question caught 90% of my class out.

Posted from TSR Mobile

Reply 350

OP

Original post by geeky_penguin

Thank you so much! I normally use the heinemann text book for the questions but it just confuses me in the trig topic. I will definitely take a look at the CGP book!

No worries! Hope it helps. Yeah I know what you mean. What specifically is it about C4 trig you find hard? Identities? Or the R alpha method etc?

Posted from TSR Mobile

Reply 351

OP

Original post by madmenace

Hi; you know the paining one? I'm not 100% sure why you add on 10 years when solving for t.... also why does it roll into 2018 beacuse it's 2017.something

Basically you want to know the value of time

T

years after 1991 when the two paintings are of equal value.

The value of the first painting is given by

V=5000p^t

, t years after 1st April 2001.

The value of the second painting is given by

W=2500q^t

, t years after 1st April 1991.

Hence,

T

years after 1991, the number of years the first painting is raised to is

T-10

, because if you think about it, it has started counting 10 years after the second painting has, meaning it always lags behind by 10 years.

This means that:

5000p^{T-10}=2500q^T

Rearranging from this point using logs gives the required equation.

It rolls into

2018

because

t=\frac{10ln(15)}{ln(5)}=16.79...

.

If you think about it,

16.79...

years after 1st April 2001 brings you just into

2018

, as the year starts with a base case in April and not January.

Does that help?

Posted from TSR Mobile

(edited 8 years ago)

Reply 352

the_googly

7

need 86 ums to get A overall. will I do it...?

Posted from TSR Mobile

Reply 353

OP

Original post by the_googly

need 86 ums to get A overall. will I do it...?

Posted from TSR Mobile

How have you been doing on past papers?

Posted from TSR Mobile

Reply 354

Jimmy20002012

4

Can anyone help me on part bii, finding coordinate of C. Since I know the length of AD, and this is the same length as BC, so I can use this. Also I know that C has coordinate in terms of mu as it lies on L2. I have used the distance formula and got a quadratic in mu and solved, to find mu as 5/7 and 1, how do I know which one to choose?? :smile:

thanks

ImageUploadedByStudent Room1431263169.167911.jpg

Reply 355

OP

Original post by Jimmy20002012

Can anyone help me on part bii, finding coordinate of C. Since I know the length of AD, and this is the same length as BC, so I can use this. Also I know that C has coordinate in terms of mu as it lies on L2. I have used the distance formula and got a quadratic in mu and solved, to find mu as 5/7 and 1, how do I know which one to choose?? :smile:

thanks

Does the mark scheme say which is the right one to choose? I'm confused as they're both viable options.

Posted from TSR Mobile

Reply 356

Jimmy20002012

4

Original post by CD223

Does the mark scheme say which is the right one to choose? I'm confused as they're both viable options.

Posted from TSR Mobile

They choose mu=5/7 but not sure why. Here is the mark scheme:

ImageUploadedByStudent Room1431272270.105938.jpg

Reply 357

OP

Original post by Jimmy20002012

They choose mu=5/7 but not sure why. Here is the mark scheme:

ImageUploadedByStudent Room1431272270.105938.jpg

Because you solved for where the isocles triangle meets l2
Which means its 2 places
So you pick the one that is smaller
Otherwise you would be using the value to the right of C, where the other nonexistent side meets the line2

You choose 5/7 because its more left of B

The way I thought of it is if you sub in P=1, then you would get an X co-ordinate back that is greater than X-co-ord of B, and therefore it must be the right side of B ( as my diagram shows) but because when you sub in 5/7, you get x<-2, you must of got the right point because its to the left of B

ImageUploadedByStudent Room1431275102.346725.jpg

ImageUploadedByStudent Room1431275102.346725.jpg

Reply 358

Jimmy20002012

4

Original post by CD223

Because you solved for where the isocles triangle meets l2
Which means its 2 places
So you pick the one that is smaller
Otherwise you would be using the value to the right of C, where the other nonexistent side meets the line2

You choose 5/7 because its more left of B

The way I thought of it is if you sub in P=1, then you would get an X co-ordinate back that is greater than X-co-ord of B, and therefore it must be the right side of B ( as my diagram shows) but because when you sub in 5/7, you get x<-2, you must of got the right point because its to the left of B

ImageUploadedByStudent Room1431275102.346725.jpg

Ahhhh right I get that now!! Thanks :biggrin: