... =ờờ-+ờ=ờở ã Vi BA2 455 547 = : chn A = 47 ị B = 2 455 5 ị d: ( )xy47(2)2 455 5(6)0 +-= ã Vi BA2 455 547-+= : chn A = 47 ị B = 2 455 5-+ ị d: ( )xy47(2)2 455 5(6)0-+-+-= 2) (P) cú ... ti O. Khi ú dOd 52 (,)2= . Gi s phng trỡnh ng thng d: AxByAB22(2)(6)0(0)-+-=+ạ Ta cú: dOd 52 (,)2= ABAB222 652 2 =+ BABA224748170+-= BABA2 455 5472 455 547ộ =ờờ-+ờ=ờở ... xt26p=-, PT tr thnh: ttttcoscos2cos3cos40+++= ttt 5 4cos.cos.cos022= tttcos02cos0 5 cos02ộ=ờờ=ờờ=ờở tmtlkt(21)22 55 pppppộ=+ờ=+ờờờ=+ờở ã Vi tmxm(21)(42)3ppp=+ị=++...