《人教版八年级上册数学《12.2 第3课时 “角边角”、“角角边”》教学课件》由会员分享,可在线阅读,更多相关《人教版八年级上册数学《12.2 第3课时 “角边角”、“角角边”》教学课件(23页珍藏版)》请在金锄头文库上搜索。
1、12.2, ,3 ,1ASAAAS 2ASAAAS,? ,? ,ABCA B C A B =AB A =A B =B ().A B C ABC,A,B,C,E,D, 1AB=AB; 2ABDAB =AEBA =BADBEC,(ASA,1 ABCDCBACB DBC ABCDCB,ABCDCB( BCCB ACBDBC,ABCDCB,ABCDCBASA,2 DABEACAB=AC, B=C,AD=AE,ACDABE,AD=AE,ACDABE,A=A AC=AB C=B ,ACDABEASA,AD=AE,6045453cm,11,. AAS,3ABCDEFADB EBC=EF.ABCDEF,BE
2、BCEF CF,ABCA+B+C180,ABCDEFASA,C180AB, F180DE, ADB E,CF,ABCDEF,4 ABCBAC90ABACmABDmCEmDE.(1)BDAAEC,(1)BDmCEm ADBCEA90 ABDBAD90. ABAC BADCAE90 ABDCAE. BDAAEC,ADB=CEA=90 ABDCAE, ABAC,BDAAEC(AAS,2)DEBDCE,BDAEADCE DEDAAEBDCE,BDAAEC,1. ABCDEFABDEBEABCDEF AACDF BBCEF CAD DCF 2. ABCABCA44B67C69 A44ACAC A B C D,A,B,A,B,C,D,E,F,3.ACB=DFEBC=EF ABCDEF ,B=E,A=D, AC=DF,ASA,AAS,SAS,AB=DE,ABDE,4. ABBCADDC1=2, AB=AD, ABBCADDC,B=D=90,ABCADC,ABCADCAAS,AB=AD,? ,?,𣺴1,ABC ABC ADA D ABC ABC.AD AD 仰,ABC ABC AB=ABABD=ABD. ADBCADBCADB=ADB. ABDABD ADB=ADB ABD=ABD AB=AB ABDABD.AD=AD, , ASA,淶 ,