David M. answered 04/30/20
The equation of a circle is (x-h)2 + (y-k)2 = r2, where (h,k) is the center of the circle and "r" is the radius. The center point of the circle will be the midpoint of the diameter. The endpoints of the diameter are (5,1) and (3,-1) and the midpoint, (h,k), is found by ((5+3)/2,(1-1)/2) = (8/2,0/2) = (4,0). Therefore, h = 4 and k = 0. To find the radius, r, we can find the distance from (4,0) to (5,1) by √((x2 - x1)2 + (y2 - y1)2):
r = √((5-4)2 + (1 - 0)2)
r = √(12 + 12)
r = √2
Put these values, h = 4, k = 0 and r = √2, into the formula for a circle we get:
(x-h)2 + (y-k)2 = r2
(x-4)2 + (y-0)2 = (√2)2
(x-4)2 + y2 = 2
Hope this helps!