If a and b denote the vectors OA and OB, indicate on the same diagram the vectors OC and OD denoted by a+ b and a - b. Draw on another diagram the vector OE denoted by a +2b. ABCD is a square and P, Q are the midpoints of BC, CD respectively. If AP = a and AQ = b, find in terms of a and b, the directed line segments (i) AB, (ii) AD, (iii) BD and (iv) AC.