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                                          .

49 ( )               35 ( )             32 ( )        7 ()

x +y                                y  x [AMC82009] ( )

                      . 360y                    360x

165 ( )              115 ( )            85 ( )        80 ( )

    0          )             DC B A             [AMC82009] (  )
                                                              )
9()                                                   (9

                    AB                          AB
               −C A                       +C A

                          A                    DA

                                       D

                     7( )               6( )          5 ()

                                                [AMC82010] (

                  .

          8 11 AMC 8

         .9

        AMC 8

29 ( )               28 ( )            27 ( )         26 ( )
   85   86   87   88   89   90   91   92   93   94   95