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Edexcel Core 3 - 21st June 2016 AM Watch

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    (Original post by Tow)
    Jw. Someone posted this:
    http://www.thestudentroom.co.uk/atta...6&d=1466461962

    for d) would you look at when cos does 2 repeats and then find t for that, assuming you let theta = pi(t)/5?
    I remember this was our mock paper in Year 13. It seems your reasoning is correct.
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    (Original post by 13 1 20 8 42)
    I remember this was our mock paper in Year 13. It seems your reasoning is correct.
    does that mean u do 4pi + alpha = pi(t)/5 ?
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    Am I right in thinking only a 'one to one' has an inverse function whereas 'many to one' and 'one to many' need restrictions to have an inverse function (like x>0)?
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    (Original post by Mathskid137)
    Am I right in thinking only a 'one to one' has an inverse function whereas 'many to one' and 'one to many' need restrictions to have an inverse function (like x>0)?
    whenever a question says 'why doesnt it have an inverse' write 'many-to-one'
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    (Original post by Tow)
    does that mean u do 4pi + alpha = pi(t)/5 ?
    Well, how I would think on it is like this. Two revolutions is 4pi radians, right? Hence you want to find t such that (pi*t)/5 = 4pi and this indeed yields the correct t value
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    (Original post by 13 1 20 8 42)
    Well, how I would think on it is like this. Two revolutions is 4pi radians, right? Hence you want to find t such that (pi*t)/5 = 4pi and this indeed yields the correct t value
    that's what I was thinking, hm... not sure why i put alpha in the equation... this was a half guess though. Didn't think about it enough. So I'm guessing the answer would be found through 4pi = pi(t)/5?
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    really hoping they serve us some nice trig questions
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    Please help anyone
    (Original post by ryandaniels2015)
    thanks but does this not mean u have to show cast or graph?
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    (Original post by 13 1 20 8 42)
    Well, how I would think on it is like this. Two revolutions is 4pi radians, right? Hence you want to find t such that (pi*t)/5 = 4pi and this indeed yields the correct t value
    Also... if you don't mind, could you explain Q3c please?

    http://qualifications.pearson.com/co...e_20130613.pdf

    Not sure how/when the equation only has one solution.

    edit: Nvm khaleesi answered!
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    Right the graph of cosx in that range has two solutions for every y value between 0 & 1, but only one solution for y=-1 and for y=1.
    So set the cos part of the equation = to -1...
    R(-1) = k, so k = -R
    ...and = to 1...
    R(1) = k, so k = R

    Or look at this...
    https://07a69ccf283966549a9350d1a669...%20Edexcel.pdf
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    (Original post by khaleesi98)
    Right the graph of cosx in that range has two solutions for every y value between 0 & 1, but only one solution for y=-1 and for y=1.
    So set the cos part of the equation = to -1...
    R(-1) = k, so k = -R
    ...and = to 1...
    R(1) = k, so k = R

    Or look at this...
    https://07a69ccf283966549a9350d1a669...%20Edexcel.pdf
    Ooooooooh yeah gotcha. Thanks! Goodluck for tomorrow!
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    (Original post by Tow)
    that's what I was thinking, hm... not sure why i put alpha in the equation... this was a half guess though. Didn't think about it enough. So I'm guessing the answer would be found through 4pi = pi(t)/5?
    Yah you literally just rearrange for t there.

    (Original post by Tow)
    Also... if you don't mind, could you explain Q3c please?http://qualifications.pearson.com/co...e_20130613.pdfNot sure how/when the equation only has one solution.
    Man these are the ugliest and most boring questions around, but generally speaking you naturally use the Rcos(x-alpha) form derived, and here sketching a graph over the range 0 </=x < 360 degrees might be prudent
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    Goodnight guys and good luck!!
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    (Original post by 13 1 20 8 42)
    Well, how I would think on it is like this. Two revolutions is 4pi radians, right? Hence you want to find t such that (pi*t)/5 = 4pi and this indeed yields the correct t value
    Sorry why do you make pit/5 = 4pi. What has the pit/5 got to do with It all
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    Do you guys know when to use f '(x) to show a function is increasing or decreasing, and when to use f ''(x) ??
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    (Original post by Zacken)
    If anybody needs any urgent help, feel free to tag me and I'll respond as soon as I can.
    hi I just wanted to ask do you know which formules and Identities I need to learn of by heart for c3
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    (Original post by 5824)
    Do you guys know when to use f '(x) to show a function is increasing or decreasing, and when to use f ''(x) ??
    First derivative gives the gradient of the graph. If it yields a positive value at a particular x value, the function is increasing at that point, and vice-versa.

    The second derivative is mainly used to find the nature of stationary points (minima or maxima). A positive second derivative value (with a first derivative value of 0) indicates a minima and vice-versa.
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    guys!!whwn is your exam time (uk time )???mineis 8am


    Posted from TSR Mobile
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    I just completed the C3 June 2011 paper and got 80 something percent and for a C3 June 2015 paper I got 48/75, which I believe is 2 marks off an A since that paper was ridiculously hard. That's the highest I've got in the papers I completed today. :lol:

    Anyways, good night guys and good luck! (Even though I don't believe in it ) I hope you all get the grades/marks you want and need. :hugs:

    (Original post by MaggieXUE)
    guys!!whwn is your exam time (uk time )???mineis 8am


    Posted from TSR Mobile
    I think it is 9am for all students in UK.
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    (Original post by xdaryaxx)
    hi I just wanted to ask do you know which formules and Identities I need to learn of by heart for c3
    Nothing much, all the trig identities are given in the booklet.

    Just remember sin (theta) = cos (90-theta), and vice-versa.
 
 
 
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