平行四边形-(5).ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,1-1-,8,1.,:,A,B,ABCD,ABCDADBC,:,-.,:,.,ABCD,.,ABCD,:,O,D,B,A,C,:,A=C,，,B=D,：,A,C,ABCD,ABCD,，,ADBC,，,1,3,，,2,4,又,AC,CA,，,ABCCDA,（,ASA,）,B,D,AB=CD,又,1,4,2,3,，,BAD,BCD,ABCD,A,D,C,B,1,4,2,3,4,4,4,.,A,B,C,D,AB=CD,AD=BC,A,B,C,D,A=,C,B=D,1,2,:,ABCD,，,A=80,A,B,C,D,C=,（）,D=,（）,B=,（）,80,100,100,B=,，,C=,，,AD=,。,48,3cm,132,A,B,C,D,:,ABCD,，,A=48 BC=3cm,1,(,ADC,=,，,BCD,=,；,2,）,AB,=,，,BC,=,D,C,B,A,58,28,32,58,28,32,122,ABCD,1-.,ABCD,DEAB,，,BFCD,-,E,，,F,AE=CF,.,:,ABCD,A=C,AD=BC,DEAB,，,BFCD,AED=CFB=90,AED,CFB,AED=CFB,A=C,AD=BC,AEDCFB,（,AAS,）,AE=CF,D F C,A E B,.,.,A,B,C,D,b,a,A,B,C,D,C,ABCD,=AB+CD+BC+AD=5+5+3+3=16,（,cm,）,50-1-,ABCD,AB=5cm,BC=3cm,.,:,ABCD,(),AB=CD,，,BC=AD,AB=5cm,BC=3cm,AB=CD=5cm,，,BC=AD=3cm,A,B,C,D,50-2-,ABCD,A,=38,。,.,:,ABCD,A,=38,。,A,=,C,=38,。,，,B,=,D,ADBC,A,+,B,=180,。,B,=,D,=,180,。,-,A,=180,。,-38,。,=142,。,1.,.,2.,.,3.,.,4.,.,5.,.,P,50 (3),-,