[EckoGecko]

Write 10-0.4v^2 as a fraction => 100-4v^2/10 and then factor out 4 from numerator and factorise etc. hope this helps

[SaulRennison]

(Original post by chocolate_monster)
R=√(a^2 + b^2)
and that for the angle:
Either:
cosα = a/b
or
Sinα = b/a

That's wrong!!!

cos α = a/r (remember CAR)
sin α = b/r

[rasklatz]

(Original post by Fatima0065)
Can anyone help me do q7 iii) on jan 11:
http://www.mei.org.uk/files/papers/2011_Jan_c4.pdf
Thankyou

multiply both sides by 10 as step 1:

10 dv/dt = 100 - 4v^2

then factorise 100 - 4v^2 = 4(25-v^2) = 4 (5-v)(5+v)

then it should be fine

[Fatima0065]

(Original post by rasklatz)
multiply both sides by 10 as step 1:

10 dv/dt = 100 - 4v^2

then factorise 100 - 4v^2 = 4(25-v^2) = 4 (5-v)(5+v)

then it should be fine

Thanks your a legend!

[Fatima0065]

(Original post by EckoGecko)
Write 10-0.4v^2 as a fraction => 100-4v^2/10 and then factor out 4 from numerator and factorise etc. hope this helps

Thanks

[NoFunnyBusiness]

(Original post by rosie12)
is anyone able to help me.. jan 2011, question 8i
its a diagram of a searchlight and it says find AC in terms of alpha. just don't understand!
http://www.mei.org.uk/files/papers/2011_Jan_c4.pdf

AC = 5/cos(alpha)

(AGF) is a triangle with AC as a 90degrees to GF

Using the sin rule:

AC/sin(90 - beta) = CF/sin(beta)

Rearrange:

CF = AC(sin(beta))/sin(90-beta)

Sin(90-beta)=cos beta

CF = ACsin(beta)/cos(beta) = ACtan(beta)

You know AC = 5/cos(alpha)

therefore CF = (5/cos(alpha)) x tan(beta) = 5 sec(alpha) tan (beta)

So GF = 2 x 5 sec(alpha) tan (beta) = 10 sec(alpha) tan (beta)

Can't believe I didn't see that the first time...but seriously if it's 3 marks just keep calm and carry on, then come back to it.

[James4821]

hi guys..... on the June 2011 C4 paper on q7ii) it asks you to find the angle between the horizontal and the plane ABC. The mark scheme has the horizontal as (0)
(0)
(1) .....but i don't understand why it is that. Could someone please explain and also then clarify what the vertical is?

[SS*]

Guys, today I did Jan 2011, June 2011 and Jan 2012. Previously I had done from Jan 08-Jun 10, and they were fine.

But I really struggled with the section Bs in june 2011 and jan 2012 for some reason...
Does anybody else feel the difficulty of Section B has increased?

[NoFunnyBusiness]

(Original post by James4821)
hi guys..... on the June 2011 C4 paper on q7ii) it asks you to find the angle between the horizontal and the plane ABC. The mark scheme has the horizontal as (0)
(0)
(1) .....but i don't understand why it is that. Could someone please explain and also then clarify what the vertical is?

If you hold your pen to the your table, the only way you can adjust the angle is by increasing the z-coordinates. If you take your flat table to be the horizontal x and y -axis of fig. 7.

If you're only adjust the z-coordinates the the y and x are irrelevant...therefore zero

This probably makes no sense


OR if you see it as making an angle with the vertical plane, then subtracting it from 180 to give an acute angle

[NoFunnyBusiness]

(Original post by SS*)
Guys, today I did Jan 2011, June 2011 and Jan 2012. Previously I had done from Jan 08-Jun 10, and they were fine.

But I really struggled with the section Bs in june 2011 and jan 2012 for some reason...
Does anybody else feel the difficulty of Section B has increased?

Which parts of each section?

[SaulRennison]

(Original post by SS*)
Guys, today I did Jan 2011, June 2011 and Jan 2012. Previously I had done from Jan 08-Jun 10, and they were fine.

But I really struggled with the section Bs in june 2011 and jan 2012 for some reason...
Does anybody else feel the difficulty of Section B has increased?

The 2011 and 2012 exams are hard, check the variation of the A grade boundaries:
http://screencast.com/t/whjm2hhP4hax

Don't worry about it, as long as your mark difference wasn't huge (e.g. 6 marks), then your UMS will probably be consistent.

Good luck tomorrow!

[Jodieeee....]

(Original post by SaulRennison)
The 2011 and 2012 exams are hard, check the variation of the A grade boundaries:
http://screencast.com/t/enELJUyV

Don't worry about it, as long as your mark difference wasn't huge (e.g. 6 marks), then your UMS will probably be consistent.

Good luck tomorrow!

I swear that Jan 12 was 64 for an A and June 11 was 63. Two of the lowest grade boundaries since June 2010

[SaulRennison]

(Original post by Jodieeee....)
I swear that Jan 12 was 64 for an A and June 11 was 63. Two of the lowest grade boundaries since June 2010

That's exactly what the graph says! and the lowest grade boundaries were June 2006 (57 for A)

[Jodieeee....]

(Original post by SaulRennison)
That's exactly what the graph says! and the lowest grade boundaries were June 2006 (57 for A)

Oh my god. You wouldnt think I was taking maths a level would you :P
no I read the bottom... Whats that bit about then??

[ILM16]

(Original post by SaulRennison)
That's exactly what the graph says! and the lowest grade boundaries were June 2006 (57 for A)

The table at the bottom?

[Jodieeee....]

(Original post by ILM16)
The table at the bottom?

Yuss, where it says A Grade Boundary - it says Jan 12 was 77 and its not percentage because the percentage is 71%

[SaulRennison]

(Original post by ILM16)
The table at the bottom?

(Original post by Jodieeee....)
Yuss, where it says A Grade Boundary - it says Jan 12 was 77 and its not percentage because the percentage is 71%

Sorry guys I'm blind, I've sorted the table out (the values were in the wrong order)

http://screencast.com/t/whjm2hhP4hax

[SS*]

(Original post by NoFunnyBusiness)
Which parts of each section?

Mostly the differential equations, but sometimes the long problem solving trig/vector question like the very last question on Jan 2011.

(Original post by SaulRennison)
The 2011 and 2012 exams are hard, check the variation of the A grade boundaries:
http://screencast.com/t/whjm2hhP4hax

Don't worry about it, as long as your mark difference wasn't huge (e.g. 6 marks), then your UMS will probably be consistent.

Good luck tomorrow!

Ah this makes me feel much better! Thank you very much. Good luck to you too

How many, if any, comprehension papers have people done? I'm kind of worried we can't really prepare for them!

[SaulRennison]

(Original post by SS*)
How many, if any, comprehension papers have people done? I'm kind of worried we can't really prepare for them!

None

[rasklatz]

(Original post by SS*)
Mostly the differential equations, but sometimes the long problem solving trig/vector question like the very last question on Jan 2011.



Ah this makes me feel much better! Thank you very much. Good luck to you too

How many, if any, comprehension papers have people done? I'm kind of worried we can't really prepare for them!

3 : most variable thing ever. One year you could get 18 marks blindfolded the other year, I can't even see what answer they want