... Mcúdng 2 3 2 1( ) : ( )( 2) 2 a y x a a a - - D = - + - -0 ,25 Gi A lgiaocatimcnngvi ( ) D ,suyra6 (2 2) 2 A a + -Blgiaocatimcnngangvi ( ) D ,suyra (2 22) B a -0 ,25 bKhiú 2 236 (2 4)( 2) AB ... .Vỡ(S)qua A, B,C,Dnờntacúh 2 2 2 3 2 4 5 2 16 9 a b c d a c db d a d + + + = - ỡ ù - + + = - ù ớ - + = - ù ù + = - ợ0 ,25 Giihtrờntac 2, 2, 3, 3a b c d = - = = - =Vyphngtrỡnhmtcu 2 2 2 ( ... + =0 ,25 im (01 )A AC AD A = ầ ị .Gis ( 1 )C c c - .Theo bi ra 2 2 2 4 2 2AC c c c = = = = -. Do honh im C õm nờn( 23 )C -0 ,25 GiJltrungimACsuy ra ( 12) J - ,ngthngBDquaJvvuụnggúcviACcúphngtrỡnh...