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→      →                                                        16
                    12.  PS   = 2QM                                    (b)      4fx  =   k  x
                             →
                                  →
                         = 2(QP + PM)                                                 4
                                     3
                                         2
                            1
                         = 2 –2i – 3j +  i + j                                    f  =  k
                                     2
                         = –i – 4j                                         12(k – 1) y = 18(1 – f )y
                                                            [3]               k
                                  →   →                                                1   4 2
                    13.  3rp + 5q = 4s(OP + PA)                              2(k – 1)  = 3k 1 –  k
                                    3 →
                                         2
                                1
                      3rp + 5q = 4s p +  PQ                                       k  = 10
                                    5
 =  1                               3 →     →                             f =  2
                                3
                                               4
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 2                    3rp + 5q = 4s p +  (PO + OQ)                           5                               [4]
                                    5
 = √3                               3
                                3
                                             4
                      3rp + 5q = 4s p +  (–p + 5q)                     (c)  AD  =  √OA  + OD
                                                                                         2
                                                                                    2
                                    5
 = √(7)  –                          3                                     AD  =  √(4x)  + (18y)
 2
                                                                                    2
                                                                                           2
                                           4
                                3
                      3rp + 5q = 4s p –  p + 3q                           AD  =  √16x  + 324y
                                    5
                                                                                          2
                                                                                    2
 2
 2
                                        2
 =  1 8  + 3          3rp + 5q = 4s 1  2 5  p + 3q                        AD  =  √16 + 324(1.5)
                                                                                           2
 2
 1                             8                                          AD  = 27.295
 = 2  2               3rp + 5q =  sp + 12sq                                     2
                               5
 =                        5q  = 12sq                                      CD  =  (27.295)
                                                                                5
                            s  =   5                                          = 10.92
                               12
                               8                                                                             [3]
                          3rp  =  sp                                          →    →    →
                               5                                     15.  (a)  (i)  SP   = SQ + QP
                                 1 2
                           3r  =  8 5                                            = –8y + 4x
                               5 12                                                                          [1]
                                                                              →
                                                                                   →
                                                                                        →
                            r  =  2                                       (ii) RP  = RQ + QP
                               9
                                                            [7]                    1 →    →
                                                                                 =   SQ + QP
                             →     →   →                                           4
                    14.  (a)  (i)  OC  = OE + EC                                 =  1 (–8y) + 4x
                                   2 →   1 →                                       4
                                 =  OD +   EB                                    = –2y + 4x
                                   3     k                                                                   [2]
                                           1 →
                                                  →
                                 =  2 (18y) +  (EO + OB)                   →    →
                                   3       k                           (b)  PT = kPR
                                       1
                                 = 12y +  (–12y + 16x)                       = 2ky – 4kx
                                       k                                   →   →    →
                                                                           PT =  PS  +  ST
                                 =  12(k – 1) y +  16 x                      = 8y – 4x + h(2x – 3y)
                                      k       k                              = (8 – 3h)y + (2h – 4)x
                                                            [3]
                             →     →   →                                    8 – 3h = 2k
                         (ii) OC  = OA + AC                                 2h – 4 = –4k
                                   1 →   →    →                             2 – h = 2k
                                 =  OB + AD – CD
                                   4                                          h = 3
                                   1 →   →    →                                    1
                                 =  OB + AD – fAD                             k = –
                                   4                                               2                         [4]
                                   1 →        →
                                 =  OB + (1 – f )AD                       m   –6
                                   4                                   (c)   2  =  –4
                                   1 →         →    →                      m = 3
                                 =  OB + (1 – f )(AO + OD)
                                   4                                                                         [1]
                                 =  1 (16x) + (1 – f )(–4x + 18y)
                                   4                                 16.  Velocity vector
                                                                                           2
                                 = 4fx + 18(1 – f )y                   =  1 −7.5 − 3.3 i +  –2 – 1.4 j  km/h
                                                            [3]             1.5       1.5
                                                                       = (−7.2i − 2.267j) km/h
                                                                                                             [2]
                         Cambridge IGCSE
                                          TM
                  200     Ace Your Additional Mathematics
         Answers Add Math.indd   200                                                                             14/03/2022   12:29 PM
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