Question 666051
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Hi,
Points (1, 5) and (-7, 9) are endpoints of the diameter of a circle. 
(1, 5) and 
(-7, 9) d = {{{sqrt(8^2 + (-4)^2) = sqrt(80) = sqrt(16*5) = 4sqrt(5)}}} 
r = {{{2sqrt(5)}}}, r^2 = 20
 Midpoint = (-3,7), center of the circle
equation of the circle: {{{(x+3)^2 + (y-7)^2 = 20}}}