Edexcel C4, past paper June 2010, Question 6, STUCK!

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  1. lellsabel's Avatar
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    Edexcel C4, past paper June 2010, Question 6, STUCK!
    Hi, I'm revising for Edexcel C4, and I've got stuck on question 6 b on the June 2010 paper and I can't find any help on it anywhere! It's really starting to stress me out now!
    Here's a link to the paper:
    http://www.thestudentroom.co.uk/atta...3&d=1303768084

    I've tried changing Theta to X to make it a bit easier to understand, then I've gone on to use integration by parts, but i just can't make my numbers work, if anyone could shed some light on how to do it, it would be much appreciated!
  2. RobG93's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    in part b, you are multiplying the function of theta (in part a) by theta, so the integral becomes, 1/2theta + 7/2thetacos2theta, with respect to theta
    Then you can use integration by parts, between the limits of pi/2 and 0.

    Hope that helps.
    Last edited by RobG93; 14-06-2011 at 15:54.
  3. RobG93's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    You should get a multiple of pi^2 minus a fraction for your answer.
  4. Annonymous_47's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    Do you know what the answer is? If it's (pi^2)/16 - 1/4 then I can help you...
  5. RobG93's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    I got (pi^2)/16 - 7/4...
  6. lellsabel's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    (Original post by Annonymous_47)
    Do you know what the answer is? If it's (pi^2)/16 - 1/4 then I can help you...
    yeah, the answer is pi^2/16 - 7/4

    :/ I'm still completely stuck...
  7. lellsabel's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    (Original post by RobG93)
    I got (pi^2)/16 - 7/4...
    How?! Please help me!
  8. Annonymous_47's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    (Original post by RobG93)
    I got (pi^2)/16 - 7/4...
    Yeah that's right actually, I just found the answer
  9. Annonymous_47's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    You need to do as RobG93 said and multiply f(theta) by theta. Then ignore the theta/2 to start with and use integration by parts on 7/2thetacos2theta part. Then integrate theta/2 and add the two integrals together and apply the limits. Or is that what you were doing?
  10. lellsabel's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    I've got it now thanks guys!
  11. RobG93's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    Uploaded my solution:
    Attached Thumbnails
    Click image for larger version. 

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  12. nitez's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    Have you got the mark scheme for that paper?
  13. bethalex's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    Thank you
  14. b3ncarol's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    i didn't get part (a). can u please explain how we can prove that?
  15. Aurum's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    (Original post by b3ncarol)
    i didn't get part (a). can u please explain how we can prove that?
    

4cos^2x - 3sin^2x

= 4cos^2x-4sin^2x+sin^2x

= 4(cos^2x-sin^2x)+sin^2x

= 4cos2x + 1/2 - cos2x/2

= 7cos2x/2 + 1/2
  16. blahhblah's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    Can anyone show me how to do question 3?!
  17. gdunne42's Avatar
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    Re: Edexcel C4, past paper June 2010, Question 6, STUCK!
    (Original post by blahhblah)
    Can anyone show me how to do question 3?!
    http://www.examsolutions.co.uk/a-lev.../C4-Papers.php
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