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Maths edexcel c4 coordinate geometry Watch

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    Stuck on q 7b !! Please help!!!

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    (Original post by TenOfThem)
    \displaystyle \int y dx = \displaystyle \int y \frac{dx}{dt} dt

    How should I proceed? @@

    Thanks


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    (Original post by Lamalam)
    Stuck on q 7b !! Please help!!!

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    The integral between curve and y axis would be given by \int(x\frac{dy}{dt})dt between limits t=-\sqrt2 and t=\sqrt2
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    (Original post by brianeverit)
    The integral between curve and y axis would be given by \int(x\frac{dy}{dt})dt between limits t=-\sqrt2 and t=\sqrt2
    why square root 2 and minus square 2?
    :confused:

    how would you approach this question?

    sorry i know i am stupid ><

    thanks!
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    (Original post by Lamalam)
    why square root 2 and minus square 2?
    :confused:

    how would you approach this question?

    sorry i know i am stupid ><

    thanks!
    The limits will be the values of t which make x=0, i.e the points on the y axis.
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    (Original post by brianeverit)
    The limits will be the values of t which make x=0, i.e the points on the y axis.
    Then isnt t= -1 and 1 ?
    This is what I got when I draw the graph .
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    (Original post by Lamalam)
    Then isnt t= -1 and 1 ?
    This is what I got when I draw the graph .
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    x=0\implies t^2=2\implies t=\pm\sqrt2
    and the curve should be a parabola with horizontal axis y=0 and vertex at (-2,0)

    Sorry, my mistake. I was looking at question 8 not question 7.
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    (Original post by brianeverit)
    x=0\implies t^2=2\implies t=\pm\sqrt2
    and the curve should be a parabola with horizontal axis y=0 and vertex at (-2,0)
    I think you are looking at Q8
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    (Original post by Lamalam)
    How should I proceed? @@

    Thanks


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    the question is asking about the area of the finite region bound by the loop so your limits are wrong. And also you can take only the upper area and then multiply by 2

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    (Original post by Lamalam)
    Then isnt t= -1 and 1 ?
    This is what I got when I draw the graph .
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    you can take from 0 to 1 and then multiply by 2 as it is symmetrical around the x axis.

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    So that agrees with the book's answer?


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    (Original post by StUdEnTIGCSE)
    So that agrees with the book's answer?


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    Yes

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    (Original post by StUdEnTIGCSE)
    So that agrees with the book's answer?


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    When I looked at my answer again , I sstart wondering why I did this correctly @@ I put the two limits of intergral according to when x=0, its seems not reasonable @@,



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    (Original post by Lamalam)
    When I looked at my answer again , I sstart wondering why I did this correctly @@ I put the two limits of intergral according to when x=0, its seems not reasonable @@,



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    I started FP1 just the last month so its baffling me too.

    I'm gonna investigate it tonight :cool::rolleyes:
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    (Original post by Lamalam)
    When I looked at my answer again , I sstart wondering why I did this correctly @@ I put the two limits of intergral according to when x=0, its seems not reasonable @@,

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    I'm afraid this is beyond me :confused:
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    (Original post by TenOfThem)
    ...
    How is this possible?

    Thank you

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    (Original post by StUdEnTIGCSE)
    How is this possible?

    Thank you

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    ? I don't get what you mean
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    (Original post by Lamalam)
    ? I don't get what you mean
    That would be the answer to your confusion...hopefully
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    (Original post by StUdEnTIGCSE)
    That would be the answer to your confusion...hopefully

    umm still a bit confused, would you please explain to me further?

    thanks a lot!!
 
 
 
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