bai 9: phan tich da thuc thanh nhan tu bang cach phoi hop nhieu phuong phap

KiÓm tra bµi cò   !"#$% & '()*+,!-(./   !"#$ ! " %&' !()*+ ,-     .  . 01!234/!25*6!7!258 01!239-!25:;6!7!25< ,/ =6/!>?.;!258@*>?1!23; !25*+;!25:;!7!258A Tõ mét ®iÓm A kh«ng n»m trªn ®êng th¼ng d    0123- Trong c¸c ®êng xiªn vµ ®êng vu«ng gãc kÎ tõ mét ®iÓm ë ngoµi mét ®êng th¼ng ®Õn ®êng th¼ng ®ã, ®êng vu«ng gãc lµ ®êng ng¾n nhÊt. B/+!25*C#+kho¶ng c¸ch tõ ®iÓm A ®Õn ®êng th¼ng d ,/ D!"#$%!>99!25*+!25:; ?16!>!7!258   .  Cho h×nh 10. H·y sö dông ®Þnh lý Pitago ®Ó suy ra r»ng: a) NÕu HB > HC th× AB > AC b) NÕu AB > AC th× HB > HC c) NÕu HB = HC th× AB = AC, vµ ngîc l¹i, nÕu AB = AC th× HB = HC ,4   %   H×nh 10 , B"#$& =.!25:;?16/!>+/!258!7!25 8!* E B25:;+*F7#GHF#GHI E B25:;+#GHF*F7#GH E J7!25:;FF7@+23#,@ 7F7F!25:;