TIẾT 12 :TRUNG ĐIỂM CỦA ĐOẠN THẲNG

BGGADT BGGADT TUAN ANH-THCS KIEU PHU TUAN ANH-THCS KIEU PHU 1 1 ngêi so¹n gi¶ng: nguyÔn m¹nh hïng ngêi so¹n gi¶ng: nguyÔn m¹nh hïng Tæ TRëng tæ to¸n lÝ Tæ TRëng tæ to¸n lÝ BGGADT TUAN ANH-THCS K IEU PHU 2 KIÓM TRA BµI Cò  a b omo  m  BGGADT TUAN ANH-THCS K IEU PHU 3 TIÕT11 TIÕT11 :TRUNG §IÓM CñA :TRUNG §IÓM CñA ®o¹n th¼ng ®o¹n th¼ng 1.Trung ®iÓm cña ®o¹n th¼ng : a.®Þnh nghÜatrung ®iÓm m ab! "#$a,b %a,b& '!" ab Ma+mb=ab Ma=mb ( )&*" ab+,-.!" chÝnh gi÷a ab a b m Minh ho¹ trung ®iÓm BGGADT TUAN ANH-THCS K IEU PHU 4 TRUNG §IÓM CñA ®o¹n th¼ng TRUNG §IÓM CñA ®o¹n th¼ng */0/1i !" mn : m n i m n i m n i h1 h2 h3 BGGADT TUAN ANH-THCS K IEU PHU 5 TRUNG §IÓM CñA ®o¹n th¼ng TRUNG §IÓM CñA ®o¹n th¼ng 2.C¸ch vÏ trung ®iÓm cña ®o¹n th¼ng ®2b (34 a b m 5n6" ab ? &7® ®8abam(ab 94/m!" ab )&7g:;:< a b BGGADT TUAN ANH-THCS K IEU PHU 6 A B  c.C¸ch 3d=; ' BGGADT TUAN ANH-THCS K IEU PHU 7 TRUNG §IÓM CñA ®o¹n th¼ng TRUNG §IÓM CñA ®o¹n th¼ng 3.LuyÖn tËp : >®%?0<0 @0 ®"A!" abB C. ia=ib )C&Ia+ib=ab C&ia+ib=abia=ib C.Ia=ib=1/2 ab s s ® ® BGGADT TUAN ANH-THCS K IEU PHU 8 2.Bµi 2cabDc!"#$a,b '!" acDn !" bc.tEmn m n c a b F,GH '!" ac ( ) 1 1 2 CM AC = !" Bc ( ) 1 2 2 CN BC = *I94941 ( ) 1 1 .10 5 2 2 CM CN AC CB cm + = + = = J Dù §O¸N VÒ §é DµI MN BGGADT TUAN ANH-THCS K IEU PHU 9 4. Hø¬ng dÉn häc bµi K,-BL"  7"  7MNB O)N;sgk Dsbt BGGADT TUAN ANH-THCS K IEU PHU 10 . Cò  a b omo  m  BGGADT TUAN ANH-THCS K IEU PHU 3 TIÕT11 TIÕT11 :TRUNG §IÓM CñA :TRUNG §IÓM CñA ®o¹n th¼ng ®o¹n th¼ng 1.Trung ®iÓm cña ®o¹n th¼ng : a.®Þnh nghÜatrung