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Math Help - obtaining an equation from the equation of a circle (given a point)

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    obtaining an equation from the equation of a circle (given a point)

    Answer is to be in the form Ax + By + C = 0

    the pines passes through (3,-5) and through the center of the circle

    (x+1)^2 + (y-3)^2 = 25/4
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    Re: obtaining an equation from the equation of a circle (given a point)

    Quote Originally Posted by kingsolomonsgrave View Post
    Answer is to be in the form Ax + By + C = 0

    the pines passes through (3,-5) and through the center of the circle

    (x+1)^2 + (y-3)^2 = 25/4
    You should easily be able to find the center of the circle from that equation. If not, look up the standard form of the equation of a circle.

    Can you find the line that passes through the two points? Can you at least find the slope?
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    Re: obtaining an equation from the equation of a circle (given a point)

    the center of the circle is (-1, 3) and the slope is -2 I think so the equation would be y = -2x+1

    is that right?
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    Re: obtaining an equation from the equation of a circle (given a point)

    Quote Originally Posted by kingsolomonsgrave View Post
    the center of the circle is (-1, 3) and the slope is -2 I think so the equation would be y = -2x+1
    That's correct. But the question said to put the answer in Ax + By + C = 0 form, so get everything on one side.
    Last edited by Reckoner; June 24th 2012 at 09:49 AM.
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    Re: obtaining an equation from the equation of a circle (given a point)

    so 2x+y-1=0
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    Re: obtaining an equation from the equation of a circle (given a point)

    Quote Originally Posted by kingsolomonsgrave View Post
    so 2x+y-1=0
    Right.
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    Re: obtaining an equation from the equation of a circle (given a point)

    thanks!
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