Question 371788
Consider a right triangle whose hypotenuse is the radius of the circle, and whose one leg is half of the chord as given. Then the 3rd leg is the perpendicular bisector from the center of the circle to the given chord.  
Let the length of the given chord be c, and the radius, r.  Then by the Pythagorean Theorem, the length of the 3rd leg is {{{l = sqrt(r^2 - c^2/4)}}}.  Noting that the radius r is fixed, then shortening c would have the effect of lengthening l, which is just the distance of the chord from the center of the circle.