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    (Original post by Can of tango)
    Could anyone explain how to justify the signs when showing this. The mark scheme is very vague. Attachment 431717
    It's worth looking the bookwork up closely:

    you get to e^y = x +/- sqrt(x^2 - 1)

    and then you need to ln both sides. So apparently the +/- sign appears in the wrong place. But in fact 1/(x - sqrt(x^2 - 1) = x + sqrt(x^2 -1) so their logs are just +/- each other.

    lizard has explained the arcosh bit
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    guys how do you go about drawing polar graphs for simple ones like r=a cos 3theta or r=a sin 4theta quickly?

    it takes me ages to figure out where the dotted lines go and how to do it but sometimes you need to draw the graph for the next part of the question so i can't leave it till the end
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    Now that the horror of physics and annoyance of economics is done I am now free for maths

    How you all?
    And for those that did OCR A Physics, how was Friday for you?

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    I take a good 2 hours to do a paper, has anyone got any advice on how to get it down to 90 minutes!!
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    (Original post by ETRC)
    guys how do you go about drawing polar graphs for simple ones like r=a cos 3theta or r=a sin 4theta quickly?

    it takes me ages to figure out where the dotted lines go and how to do it but sometimes you need to draw the graph for the next part of the question so i can't leave it till the end
    You should try to remember the "standard" curves, if you do and one comes up you will save so much time.

    Just choose common values of theta to plug into your calculator, eg pi/4, pi/2, 3pi/4 etc, and try to visualise what the curve will look like.
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    (Original post by Leechayy)
    Now that the horror of physics and annoyance of economics is done I am now free for maths

    How you all?
    And for those that did OCR A Physics, how was Friday for you?

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    I had OCR B yesterday I think I managed to wing an A (hopefully) after only starting revision on Wednesday
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    (Original post by lizard54142)
    You should try to remember the "standard" curves, if you do and one comes up you will save so much time.

    Just choose common values of theta to plug into your calculator, eg pi/4, pi/2, 3pi/4 etc, and try to visualise what the curve will look like.
    i just hope a 2 mark curve comes up where you can easily visualise it by using 2 or 3 points. i am fine on most curves except the standard ones that never come up much cos they are supposed to be easier.
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    (Original post by Leechayy)
    Now that the horror of physics and annoyance of economics is done I am now free for maths

    How you all?
    And for those that did OCR A Physics, how was Friday for you?

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    i think i got above 80/100 and i just need an A so alright i guess

    i hope g484 doesn't mess me up cos that paper was crap
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    (Original post by ETRC)
    i just hope a 2 mark curve comes up where you can easily visualise it by using 2 or 3 points. i am fine on most curves except the standard ones that never come up much cos they are supposed to be easier.
    June 2010 the paper I am doing at the moment... 12 mark question on polar curves.

    My worst nightmare (the question was actually pretty straightforward in the end).
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    (Original post by lizard54142)
    June 2010 the paper I am doing at the moment... 12 mark question on polar curves.

    My worst nightmare (the question was actually pretty straightforward in the end).
    i don't mind area of the polar curves which are alright but i hate it when they ask anything else
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    Can someone slowly go through the substitution method of integration, mainly how you know what to substitute x as, iv attached an example of a worked solution to question 1bii) on Summer 2011.

    I normally do it another method but when substitutions are required i get very confused!
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    (Original post by drslimey)
    Can someone slowly go through the substitution method of integration, mainly how you know what to substitute x as, iv attached an example of a worked solution to question 1bii) on Summer 2011.

    I normally do it another method but when substitutions are required i get very confused!
    Which bit don't you understand?

    You notice that the denominator in the integral is of the form:

    1 + kx^2 where k is a square number, so we can re-write this as:

    1+ (2x)^2 .

    We already can tell that the substitution required is trigonometric just by looking at it, so we consider trig identities of the form "1 + x^2 ". 1 + tan^2x fits this nicely, so we want:

    2x= \tan u \Rightarrow x = \frac{1}{2} \tan u
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    (Original post by lizard54142)
    Which bit don't you understand?

    You notice that the denominator in the integral is of the form:

    1 + kx^2 where k is a square number, so we can re-write this as:

    1+ (2x)^2 .

    We already can tell that the substitution required is trigonometric just by looking at it, so we consider trig identities of the form "1 + x^2 ". 1 + tan^2x fits this nicely, so we want:

    2x= \tan u \Rightarrow x = \frac{1}{2} \tan u

    Thanks you cleared that up a bit!

    Also one more question, is this a perfectly acceptable way of showing all the roots on an aground diagram... as in the lines drawn out to out point?
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    (Original post by drslimey)
    Thanks you cleared that up a bit!

    Also one more question, is this a perfectly acceptable way of showing all the roots on an aground diagram... as in the lines drawn out to out point?
    Yeah that shouldn't be an issue... why would you do it like that though?
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    (Original post by drslimey)
    I take a good 2 hours to do a paper, has anyone got any advice on how to get it down to 90 minutes!!
    Get used to spotting the tricks in FP2. More than most other modules, FP2 mostly consists of a number of ideas for each topic, which while tricky (e.g. C + jS geometric series stuff), is almost always essentially the same question.
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    In the past papers I've got grades ranging from As to Us... So this year's paper should be interesting 😂

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    (Original post by Dan205)
    In the past papers I've got grades ranging from As to Us... So this year's paper should be interesting 😂

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    You might look at why? Are there some topics you don't get? Are you just getting better as you practise?
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    Just remembered how irritating De Moivre's stuff is...

    Quick break, bit of memory-jogging then I should be ready for tomorrow's final cram
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    (Original post by ian.slater)
    You might look at why? Are there some topics you don't get? Are you just getting better as you practise?
    Mostly it's the calculus techniques; I didn't work hard at all for c3 and c4 last year so I didn't learn how to do substitution integrations etc :/
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    what does ag mean on the mark scheme?
 
 
 

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