题目

如图，在矩形ABCD中，AB＝8，BC＝6，E为AD上一点，将△BAE绕点B顺时针旋转得到△BA′E′，当点A′，E′分别落在BD，CD上时，则DE的长为_____． 答案：【答案】【解析】根据勾股定理可求BD=10，由旋转的性质可得AE=A'E，AB=A'B=8，∠BA'E'=90°，由△BCD∽△E'A'D，可得，可得A'E'=AE=，即可求DE的长．∵四边形ABCD是矩形∴∠DAB＝∠C＝90°，AD＝BC＝6，AB＝CD＝8，∴BD＝＝10，∵将△BAE绕点B顺时针旋转得到△BA′E′，∴AE＝A'E，AB＝A'B＝8，∠BA'E'＝90°∴A'D＝BD﹣BA'＝2Tell them the basic proposal and what they can gain, and ______ the big details unless they request for more information. A. bring out                  B. let out              C. leave out          D. make out