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    The circle with equation x^2+y^2=1 is stretched with scale factor 3 parallel to the x axis and with scale factor 2 parallel to the y axis. Write down the equation of the new curve

    Please explain your answer
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    (Original post by superkillball)
    The circle with equation x^2+y^2=1 is stretched with scale factor 3 parallel to the x axis and with scale factor 2 parallel to the y axis. Write down the equation of the new curve

    Please explain your answer
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    (Original post by superkillball)
    The circle with equation x^2+y^2=1 is stretched with scale factor 3 parallel to the x axis and with scale factor 2 parallel to the y axis. Write down the equation of the new curve

    Please explain your answer
    Or perhaps:

    2((1/3X)^2+Y^2-1)=0

    Cant remember, btw ignore the answer before. Casue its late and I'm tired.
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    Thanks a lot
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    Parametric equations are:

    x = 3cost, y = 2sint

    Manipulate those to get:

    x^2/9 + y^2/4 = 1
    4x^2 + 9y^2 = 36
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    (Original post by mikesgt2)
    Parametric equations are:

    x = 3cost, y = 2sint

    Manipulate those to get:

    x^2/9 + y^2/4 = 1
    4x^2 + 9y^2 = 36
    I dont understand how u do it
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    (Original post by superkillball)
    I dont understand how u do it
    Do you understand the parametric bit?


    The manipulation goes like this:

    x = 3cost, y = 2sint

    cost = x/3 => cos^2(t) = (x^2)/9
    sint = y/2 => sin^2(t) = (y^2)/4

    But: sin^2(t) + cos^2(t) = 1
    => (y^2)/4 + (x^2)/9 = 1

    Multiplying by 4*9 = 36

    4x^2 +9y^2 = 36
 
 
 
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Updated: December 13, 2003
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