step 1
Find out the midpoint
we have the points
(1,-5) and (2,12)
The formula to calculate the midpoint between two points is equal to
substitute the given values
so the midpoint is C(1.5,3.5)
step 2
we have that
the center of the circle is the midpoint C(1.5,3.5)
Find out the radius
Remember that
the distance between the center and any point that lies on the circle is equal to the radius
we have the points
C(1.5,3.5) and (2,12)
Find out the distance (radius)
substitute given values
the equation of the circle is equal to
simplify