Draw two different chords in the circle
Find the midpoint of each chord
Draw a line perpendicular to each chord through its midpoint
Locate the point where the two perpendicular bisectors intersect
That intersection point is the center of the circle
Draw two different chords in the circle
Find the midpoint of each chord
Draw a line perpendicular to each chord through its midpoint
Locate the point where the two perpendicular bisectors intersect
That intersection point is the center of the circle