To construct a circle, draw a line that represents the diameter of the circle. Bisect the line so that it is a perpendicular bisector of the diameter of the circle. Place your compass at the bisection point/midpoint and draw an arc or better still the whole circle.
Theorem: the perpendicular bisector of a chord passes through the center of a circle.
Note: a diameter of a circle is a chord that passes through the center of a circle.
I got 5 inches b/c 8-5 1/4 equals to 2 3/4. 2 3/4 is equal to two feet and 9 inches. 28 inches is equal to two feet and four inches. Nine inches minus four inches equals five inches.