IF endpoints A(-7-1) and B(5,5)

How do you determine the equation of the circle passing through AB.

Need help with this, I can fiqure this out. Which equation do I use and what would the answer be.

Thanks for your help in advance.

Joanne

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- Jan 30th 2009, 04:31 PM #1

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- Jan 30th 2009, 05:47 PM #2
Hello bradycat!

You can first use the mid-point formula to find the center of the circle:

midpoint formula says:

$\displaystyle \frac{x_1+x_2)}{2} = h $ (x coordinate of center of circle)

and you do the same for your k (y coordinate) with the y coordinates of the given points.

So for your circle:

$\displaystyle \frac{-7+5}{2} = h$

$\displaystyle \frac{-1+5}{2} = k$

So the coordinate of the center of your circle are:

(h,k) or (-1,2)

Using that, see if you can figure out the standard form equation for the circle.

Good Luck!