题目内容
.(本小题满分7分)已知:正方形
中,
,
绕点
顺时针旋转,它的两边分别交
(或它们的延长线)于点
.当
绕点
旋转到
时(如图1),易证
.
1.(1)当
绕点
旋转到
时(如图2),线段
和
之间有怎样的数量关系?写出猜想,并加以证明.
2.(2)当
绕点
旋转到如图3的位置时,线段
和
之间又有怎样的数量关系?请直接写出你的猜想.
![]()
【答案】
1.解:(1)
成立.······································································ (2分)
如图,把
绕点
顺时针
,得到
,
则可证得
三点共线(图形画正确)······ (3分)
证明过程中,
证得:
·································· (4分)
证得:
····························· (5分)
![]()
![]()
······························································································· (6分)
2.(2)
(8分)
【解析】略
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