A midpoint divides a line or a segment into two equal parts. If D is the midpoint of the segment AC and C is the midpoint of segment DB, what is the length of the segment AB, if AC = 3 cm. If D is the midpoint of AC, then AD=DC If C is the midpoint of DB, then DC=CB If AC=3cm. then then DC-3/2=1.5 If DC=1.5 then CB is 1.5 also AB=AC+CB AB=3+1.5 AB=4.5