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Circles


               to    ‾ XY    and    ‾ ON    is perpendicular to    ‾ PQ   .   But,  MN =  OM ON+
               Draw    ‾ OX   and    ‾ OP  . It implies that,     =  3cm 4.58cm+

               OX =  OP 5cm=     (radius).                                = 7.58 cm

                           1                             Therefore, the distance between the
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               But,  XM =   XY ( since XY ⊥  MN  )
                           2                             chords is 7.58 cm.
               Thus,
                      1
                XM = ×   8cm
                      2                                Exercise 5.10
                        = 4 cm .
                                                       In questions 1 to 4,  O  is the centre
               Similarly,                              of each circle. Find the value of x
                     1                                 (all measurements are in centimetres).
                PN =   PQ ( since PQ MN⊥   )
                     2                                  1.
                     1
                      = × 4cm
                     2

                       = 2 cm                                         O
               In triangle OXM, apply the Pythagoras'
                                                               7
               theorem as follows.                                     x
                ( OM ) ( ) (       XM  ) 2                 A     5    P          B
                      2
                               2
                       =
                          OX −
                      2
                                 2
                                          2
                    (  ‾ OM   )       =     (5 cm)      −        (4 cm)
                                                        2.
                                2
                          = 25  cm     – 16   cm             R
                                         2
                          = 9   cm                                 8
                               2
                   OM =    9 cm 2                                      O
                          =  3 cm                                      3
                                                                  x
               In triangle OPN, apply the Pythagoras'
                                                           A          P         B
               theorem as follows.
                      2         2       2                                                           Mathematics for Secondary Schools
                     (   ‾ ON   )       =     (   ‾ OP   )      −    (   ‾ PN   )        3.    Q
                      2
                                          2
                                 2
                     (  ‾ ON   )       =  (5  cm)     − (2  cm)       3.6       B
                              = 25  cm     − 4  cm
                                       2
                               2
                                                                    O
                                    =  21   cm                   5
                                2
                 ⇒  ON =   21cm 2
                                                           A          x         P
                             = 4 . 58 cm




                 Student\s Book Form Three         145



                                                                                          18/09/2025   09:59:48
     MATHEMATIC F3 SB.indd   145                                                          18/09/2025   09:59:48
     MATHEMATIC F3 SB.indd   145
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