Help with the part (iii) in particular. Clear explanations would
be preferable.
NOT TO SCALE
In the diagram OAB and OED are straight lines. Q is the origin. O is the midpoint of OB and E is the midpoint of AC. AC and CB = b.
Find, in terms of a and b, in its simplest form:
(i) AB
(ii) OE
(iii) the position vector of D.