9 @ @pbjïØ Üa@ @WV . 63 [AHSME 1994] ( ) 5 [AMC12A 2003] ( ) AC B B 5A . C . [AIME 2010] ( ) . 6 [MAΘ 2008] ( ) (0, 0) SACRAMENTO [MAΘ 2008] ( ) (0, 0) (4, 4) . .(0,−1) (−1, 0) (0,1) (1, 0) (4, 4) (0, 0) [MAΘ 2008] ( ) 10