25 In the diagram, A is the midpoint of OC and B is the point on OD where OB= 1/3 OD. OA = a and OB = b. (a) Express, as simply as possible, in terms of a and b (i) AB, (ii) CD. (b) E is the point on CD where CE : ED = 1 : 2 . (i) Express BE, as simply as possible, in terms of a and/or b. (ii) What special type of quadrilateral is ABEC?