Tracey M. answered 06/28/18
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Find the midpoint which will be the center of the circle.
The midpoint formula is ((x1 + x2)/2 , (y1 + y2)/2 )
(1 + 9)/2 , (7 + 1)/2
(5,4) is the center
Now the standard form for the equation of the circle is :
(x-h)2 + (y-k)2 = r2 where the center is (h,k) and r = radius
We still need the radius which is equal to the distance from either of the points to the center
The distance formula is √((x1 - x2)2 + (y1 - y2)2
so the radius is √(9-5)2 + (1-4)2
this equals √25 = 5
now we plug in 5 for r
(x-5)2 +(y-4)2 = 25