What is the equation of a circle with diameter line ab that has endpoints a(0,0) and b(8,6)

The equation of a circle is
(x-h)²+(y-k)²=r²
center is (h,k) and radius is r

find the midpoint to find the center of the circle

midpoint of (x1,y1) and (x2,y2) is ((x1+x2)/2,(y1+y2)/2)
so midpoint of (0,0) and (8,6) is ((0+8)/2,(0+6)/2)=(8/2,6/2)=(4,3)

(x-4)²+(y-3)²=r²
input a point to find r
(0,0)
(0-4)²+(0-3)²=r²
16+9=r²
25=r²
5=r

anwya equation is
(x-4)²+(y-3)²=5²