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    (Original post by ridirahman)
    Attachment 425681

    How would you draw that??
    I need to draw it to find the domain
    You cant really find the domain from a graph in this case, you'd need to know to use common sense that ln(x+2) x+2 cannot be zero as ln0 is undefined


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    (Original post by kdevitto)
    http://qualifications.pearson.com/co...c_20100218.pdf

    Question 8 here, why does cot2x=0 become tan2x= infinity symbol?
    Could someone explain how they solved this? Thanks!
    simple! cot 2x is the same as cos2x/sin2x.

    So eventually cos2x=0 AND YOU SOLVE!! YOU WILL GET 90,270
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    (Original post by domcandrews)
    https://b3755649dbd1afe3db91a899c3b9...%20Edexcel.pdf

    Anyone help on Q2 part b, not sure where they're getting the solution from/what to use

    MS is here:
    https://b3755649dbd1afe3db91a899c3b9...%20Edexcel.pdf

    many thanks
    i'm guessing you got to cos(2x+(2pi/3)) = 1/2.

    Since you're looking for solutions in the range 0<x<pi, if we call 2x+(2pi/3) theta, then the range of theta is 2pi/3 < theta < 8pi/3. At this point you may wish to use a CAST diagram and find all the values, and pick out the ones in the range before finding the x values.
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    (Original post by BioAgent)
    For the Rcosalpha/Rsinalpha questions do you have to show all your working?
    why risk it? show all working!
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    (Original post by domcandrews)
    count me in too, started today and haven't looked at c3 since we finished it back in november, this is going to be fun loooool
    Nah I'm messing up the studentroom's high scoring pattern
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    (Original post by kdevitto)
    http://qualifications.pearson.com/co...c_20100218.pdf

    Question 8 here, why does cot2x=0 become tan2x= infinity symbol?
    Could someone explain how they solved this? Thanks!
    cot = cos/sin

    cos = 0

    2x = cos-1(0)
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    (Original post by Ripper Phoenix)
    Youll be relieved that proving by counter and stuff isnt on edexcel syllabus. Edexcel can not bring stuff outside the spec. It would result in a petition. But anyway good luck 👌🏼


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    Ah thank you! I wouldn't have known, but it's not that bad actually but cheers for the heads up!
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    Anyone got the jan 2015 ial paper?
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    (Original post by frozo123)
    Nah I'm messing up the studentroom's high scoring pattern
    AHAHA yesss
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    (Original post by Cosmi)
    http://www.examsolutions.net/a-level...6&solution=8.2

    Why isn't cos() -1? Surely -21/25 is smaller than 21/25?
    Anyone able to help with this? I've never understood this.
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    (Original post by Mrkingpenguin)
    Anyone got the jan 2015 ial paper?
    https://drive.google.com/folderview?...JHS1ZSTHM#list
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    How THE FUDGE is part a (i) the graph of f^-1(x) ?

    i thought to draw the inverse function you reflect the f(x) in the y=x line.
    Rather than imagining it through the head, is it possible to just times the co-ordinates by something to find the reflection in the y=x line Because i do not understand how they got that in part a (i)

    Someone help!
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    (Original post by Mrkingpenguin)
    Anyone got the jan 2015 ial paper?
    https://drive.google.com/folderview?...k5FZDJHS1ZSTHM
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    (Original post by Humbers)
    I feel like a butchered the answer but i got there in the end, if theres a quicker way that i missed, tell me
    Attachment 425677
    thanks guys
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    (Original post by Mrkingpenguin)
    Anyone got the jan 2015 ial paper?
    https://drive.google.com/folderview?...JHS1ZSTHM#list

    Think they combine c3/c4
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    (Original post by SeanFM)
    i'm guessing you got to cos(2x+(2pi/3)) = 1/2.

    Since you're looking for solutions in the range 0<x<pi, if we call 2x+(2pi/3) theta, then the range of theta is 2pi/3 < theta < 8pi/3. At this point you may wish to use a CAST diagram and find all the values, and pick out the ones in the range before finding the x values.
    Nope i don't understand how they got to that first bit with cos(2x + 2pi/3)??? Am i missing something silly or...?
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    (Original post by Mrkingpenguin)
    Anyone got the jan 2015 ial paper?
    its a c34 paper not a c3 paper on its own
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    (Original post by studentwiz)
    someone help
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    (Original post by domcandrews)
    Nope i don't understand how they got to that first bit with cos(2x + 2pi/3)??? Am i missing something silly or...?
    It's linked to part a. Sec(x+(pi/6)) is the same as 1/(cos(x+(pi/6)), so they've multiplied both sides by cos(x+(pi/6)) to get something of the form in part a.
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    How the FUDGE is part a (i) the graph of the inverse function? i thought the inverse function is a reflection in y=x line and i just can't see that with this graph in my head.
    Is there a way in which you can just times the co-ordinates by something to find the reflection in the y=x line??? Someone please help!
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