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    (Original post by economicss)
    Hi, please could someone explain how you find the area in question 63 of rev 2 https://8fd9eafbb84fdb32c73d8e44d980...ZweHc/REV2.pdf, is there a general method to follow when finding areas of overlapping regions? Thanks
    Well, I suppose you should start by finding the points of intersection, that's a good starting point.

    Then, look at symmetry, is the shape symmetric in the intial line? If so, you can just work out the area of the upper-half-plane and then multiply it by two to avoid weird negative area stuff cancelling things out in the bottom half.

    Draw your half angle lines on the diagram and mark them. You'll most usually need to integrate one curve and then find the rest of the shaded region by using areas of triangles or circular sectors or the like.

    (Original post by EricPiphany)
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    (Original post by Zacken)
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    I figured eventually.
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    (Original post by Zacken)
    Well, I suppose you should start by finding the points of intersection, that's a good starting point.

    Then, look at symmetry, is the shape symmetric in the intial line? If so, you can just work out the area of the upper-half-plane and then multiply it by two to avoid weird negative area stuff cancelling things out in the bottom half.

    Draw your half angle lines on the diagram and mark them. You'll most usually need to integrate one curve and then find the rest of the shaded region by using areas of triangles or circular sectors or the like.



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    Thanks, on question 63 above, the working on solutions bank is very long, would it be possible to work out the area instead by doing 2 times the integral of a(3+cos20) with limits 0 and pi/3? Thanks
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    (Original post by economicss)
    Thanks, on question 63 above, the working on solutions bank is very long, would it be possible to work out the area instead by doing 2 times the integral of a(3+cos20) with limits 0 and pi/3? Thanks
    You want the area from pi/3 to pi of the a(3+cos) curve and then multiply that by two.

    You want the area from 0 to pi/3 of the a(5-cos) curve and then multiply that by two.

    Then add the above two together.
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    (Original post by Zacken)
    You want the area from pi/3 to pi of the a(3+cos) curve and then multiply that by two.

    You want the area from 0 to pi/3 of the a(5-cos) curve and then multiply that by two.

    Then add the above two together.
    Thanks, why is the area of the first part from pi/3 to pi rather than from 0 to pi/3?
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    (Original post by economicss)
    Thanks, why is the area of the first part from pi/3 to pi rather than from 0 to pi/3?
    You should be able to see that from the diagram? The area bounded by that curve is the bit from the pi/3 to the pi.
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    (Original post by Zacken)
    You should be able to see that from the diagram? The area bounded by that curve is the bit from the pi/3 to the pi.
    Thank you, got it Please could you explain how the area if found in question 9b of this paper https://8dedc505ac3fba908c50836f5905...%20Edexcel.pdf, in particular the area of the sector of the circle, and how you know to use this? Thanks!
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    Could anyone help explain question 9b of this international paper please https://doc-0k-0g-docs.googleusercon...nJHZjNDT1U2Ukk I thought the answer would have been the integral of C1 between pi/12 and 5pi/12, why isn;t this correct? Thanks!
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    (Original post by economicss)
    Could anyone help explain question 9b of this international paper please https://doc-0k-0g-docs.googleusercon...nJHZjNDT1U2Ukk I thought the answer would have been the integral of C1 between pi/12 and 5pi/12, why isn;t this correct? Thanks!
    Zacken
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    (Original post by economicss)
    Zacken
    You'll need to tell me what paper it is because the link doesn't work.
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    (Original post by Zacken)
    You'll need to tell me what paper it is because the link doesn't work.
    Sorry, not sure what's up with the links! It's
    The F2 June 2014 IAL paper Thanks
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    (Original post by economicss)
    Sorry, not sure what's up with the links! It's
    The F2 June 2014 IAL paper Thanks
    This is what you'd get if you integrated C1 between the two limits:



    This is what you'd get if you shaded C2 between the two limits:



    So as you can see, neither one is going to get you the wanted area (sorry for the horrible paint skills!).
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    (Original post by Zacken)
    This is what you'd get if you integrated C1 between the two limits:



    This is what you'd get if you shaded C2 between the two limits:



    So as you can see, neither one is going to get you the wanted area (sorry for the horrible paint skills!).
    Wtf is this 0.0 holy..
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    (Original post by Student403)
    Wtf is this 0.0 holy..
    Have you covered polar coordinates yet? :lol:
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    (Original post by Zacken)
    Have you covered polar coordinates yet? :lol:
    No - from studying for the SATII I thought it was just r, costheta - not drawing graphs :afraid:
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    (Original post by Student403)
    No - from studying for the SATII I thought it was just r, costheta - not drawing graphs :afraid:
    It's admittedly one of the harder/hardest topics on FP2. Some practice and you'll be fine though, it's not too hard to wrap your head around!
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    (Original post by Zacken)
    It's admittedly one of the harder/hardest topics on FP2. Some practice and you'll be fine though, it's not too hard to wrap your head around!
    Sounds good As long as it goes in to my FX 9860 I'm happy :lol:
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    (Original post by Zacken)
    This is what you'd get if you integrated C1 between the two limits:



    This is what you'd get if you shaded C2 between the two limits:



    So as you can see, neither one is going to get you the wanted area (sorry for the horrible paint skills!).
    Thank you! What would you say is the best method for this question?
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    (Original post by economicss)
    Thank you! What would you say is the best method for this question?
    Area of secror + 2 left over bits from C1, I'll upload a sketch tomorrow morning if you quote me and remind me.
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    (Original post by Zacken)
    Area of secror + 2 left over bits from C1, I'll upload a sketch tomorrow morning if you quote me and remind me.
    Zacken Please could you upload a sketch, thanks so much!
 
 
 
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