The diameter of the circle can be found by using the distance formula with the two points given...
d^2=(4--10)^2+(6--2)^2
d^2=14^2+8^2
d^2=260
d=√260
d=2√65
Since the radius is just half of the diameter, r= √65
The center of the circle will just be the midpoint (the average of the coordinates of the two endpoints) of the two points given so:
c=(-10+4)/2, (-2+6)/2
c=(-3,2)
The standard form of the circle is:
(x-h)^2+(y-k)^2=r^2, where (h,k) is the center of the circle so we can say:
(x+3)^2+(y-2)^2=65