第1个回答 2020-05-21
在长方形中,有:∠ACB=∠CAD,△ABC≌△CDA;
ABCD沿对角线AC折叠后,∠ACB=∠ACB′,△ABC≌△AB′C;
(1)证:
∠ACB=∠CAD;
ABCD沿对角线AC折叠后,∠ACB=∠ACB′;
==>
∠CAD=∠ACB;
==>
△AMC是
等腰三角形
(2)证:
△ABC≌△CDA,△ABC≌△AB′C
==>△ABC≌△AB′C;
==>AB′=CD;
AD=BC=B′C
===>对角线相等
∠ACD≠90º
===>四边形ACDB'是
等腰梯形