a) There are two other significant points on the line segment OH, name them.
The centroid, G, and the center of the nine-points circle, N.
b) Draw a diagram which shows the relative positions of these four points.
c) If the line segment OH has a length of 18 units, what are the lengths of the three segments determined by these four points?
As N is the midpoint of OH, HN = 9. Since G trisects OH, GO = 6. Since the total length is 18, NG = 3.