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3

                 For each of the following, calculate the value of x.
                 (a)           x cm           (b)
                                                   x cm       24 cm
                      12 cm
                                 16 cm                      26 cm                Smart
                                                                                 Smart

                                                                                The length of the
                                  2
                            2
                 (a)  x  = 12  + 16           (b)  26  = x  + 24 2              hypotenuse can be
                                                         2
                                                    2
                      2
                                                    2
                                                          2
                       = 144 + 256                 x  = 26  – 24 2              calculated using the Pol
                                                                                function. For instance,
                       = 400                          = 676 – 576               Example 3(a),
                         
                     x  =  400                        = 100                     press   Pol(   1   2   ,
                                                        
                       = 20                         x =  100
                                                      = 10                       1   6   )   =
                             4
                 Calculate the length of PQ in each of the following diagrams.     id   ou    now
                 (a)                          (b)     S   8 cm                  Three numbers a, b and c
                        R       12 cm                          R                           2   2  2
                  3 cm                      Q                  6 cm             that satisfy c  = a  + b
                   S                                           Q                are known as a
                  4 cm                            15 cm                         Pythagorean triples (or
                                                                                triplets). For example,
                        P                                                       (3, 4, 5), (5, 12, 13),
                                                       P                        (7, 24, 25) and so forth.

                             2
                 (a)  PR  = 3  + 4 2          (b)  QS  = 6  + 8 2
                        2
                                                     2
                                                         2
                         = 9 + 16                     = 36 + 64
                         = 25                         = 100
                                                           2
                        2
                                                     2
                     PQ  = PR  + RQ  2            PS  = QS  + PQ  2
                              2
                                                           2
                                                     2
                         = 25 + 12 2              PQ  = PS  – QS 2
                                                          2
                         = 169                        = 15  – 100
                           
                     PQ  =  169                       = 125
                                                        
                         = 13 cm                  PQ  =  125
                                                      = 11.18 cm (2 decimal places)
                     Self Practice      13.1c                                                                 CHAPTER
                 1.  For each of the following, calculate the value of x. Give your answer correct to two
                     decimal places if necessary.                                                             13
                     (a)                  (b)      x cm       (c)                  (d)          1.0 m
                          x cm      6 cm                                    9 cm       x m
                                          7 cm       25 cm         x cm                        1.2 m
                             8 cm
                                                                         14 cm


                                                                                                       297
                                                                           The Pythagoras’ Theorem



       13 TB Math F1.indd   297                                                                       11/10/16   12:22 PM
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