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    (Original post by Maham88)
    thats what i did but are they doing here page 9 https://a48aca6bcd82b5ada594d7397b73...%20koli248.pdf
    I think they converted it to 2cos2ysin2y then used factor formulae
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    (Original post by frozo123)
    I think they converted it to 2cos2ysin2y then used factor formulae
    No they just looked at part a since it gives you it there
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    (Original post by anonwinner)
    Look at part a of that question... It literally gives you it
    oh right , thanks
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    (Original post by ridirahman)
    As long as there isn't a really big difficult vectors question I'll be fine
    I hope the differential equation is like Q2 and then vector question is Q7
    lol that will make my day
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    (Original post by 286001)
    Can someone help me on part iiI know that when two lines are parallel a.b=|a||b| but then I have too many unknowns Attachment 429579
    Which paper is this?
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    (Original post by studentwiz)
    do you think the paper would be harder this year?
    To you question about integration by recognition its sort of like this

    { <- pretend that's an integral sign


    { [f'(x)][f(x)]^n = [f(x)^(n+1)]/(n+1)

    its difficult to explain but you look for 'reverse of a differentiation'

    if you differentiated a function

    [f(x)]^n -> n[f'(x)][f(x)]^(n-1)

    and you have to look for the reverse when integrating, thats the best i can explain it but it's not an easy concept to show in the chat :L
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    (Original post by Maham88)
    oh right , thanks
    No problem, always keep your eye out for things like that
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    (Original post by 286001)
    Can someone help me on part iiI know that when two lines are parallel a.b=|a||b| but then I have too many unknowns Attachment 429579
    The line that OA is a part of has the same direction vector as l2
    Since OA goes through O, you can thus say OA = k(direction vector)
    Then you just solve for the distance
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    alright **** this... lets just get this over a done with... lets just focus on C4 and try not fail too hard...
    good luck everyone
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    (Original post by frozo123)
    I hope the differential equation is like Q2 and then vector question is Q7
    lol that will make my day
    that would kill me Q7's are usually hard and I can't do any hard vectors Q's
    I just hope there are no more than 8 questions unlike the c3 exam
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    (Original post by Humbers)
    To you question about integration by recognition its sort of like this

    { <- pretend that's an integral sign


    { [f'(x)][f(x)]^n = [f(x)^(n+1)]/(n+1)

    its difficult to explain but you look for 'reverse of a differentiation'

    if you differentiated a function

    [f(x)]^n -> n[f'(x)][f(x)]^(n-1)

    and you have to look for the reverse when integrating, thats the best i can explain it but it's not an easy concept to show in the chat :L
    i sort of see your point, what method do you usually use?
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    when we are finding the volume of a cone is the length the r value or the width the r value??
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    (Original post by studentwiz)
    i sort of see your point, what method do you usually use?
    you have to recognise which method you'll have to use hence the name integration by recognition
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    (Original post by studentwiz)
    when we are finding the volume of a cone is the length the r value or the width the r value??
    r is the radius of the circle and h is the slanted height of the cone.
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    (Original post by studentwiz)
    i sort of see your point, what method do you usually use?
    If i can use recognition then i'll use that because its the fastest
    I will only ever use substitution when the question tells me to
    and if i cant be recognized i'll use by parts


    heres an example of recognition that might make more sense

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    (Original post by 286001)
    Can someone help me on part iiI know that when two lines are parallel a.b=|a||b| but then I have too many unknowns Attachment 429579
    No it's not, what have you done so far?
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    Can anyone give me an example of a trig integration by parts where I have to sub it back in at the end? Don't think I've come across one.
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    Alright, let's do this. Good luck guys, off to school.
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    Okay, good luck guys! Hope the paper is easy since c3 was hard af. Off to school.
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    (Original post by studentwiz)
    when we are finding the volume of a cone is the length the r value or the width the r value??

    r = radius so it will be the width of the base i guess

    if you're asking because of that volume of revolution question in the recent paper (can't remember which) r = the y value

    Just think about how it will look when rotated and its the radius of the cone formed
 
 
 
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