The equation of a circle is written as (x-h)^2 + (y-k)^2 = r^r
H and k are the x and y coordinates of the center of the circle and r is the radius.
You are given the diameter coordinates so find the halfway point for the center then calculate the radius
Midpoint = (x1 +x2)/2, (y1 + y2)/2
Midpoint = (7 + -1)/2, (-3 +7)/2
Midpoint = 6/2, 4/2
Midpoint = 3,2
So h = 3 and k = 2
Now find radius by finding the distance between the center point and an end point.
Distance = sqrt(41)
Equation of the circle:
(X-3)^2 + (y-2)^2 = 41