(1)在Rt△ABE和Rt△AGE中,,, ∴△ABE≌△AGE. ∴.················································· 1分 同理,. ∴.······································································ 2分 (2).······································································ 3分 ∵,, ∴. ∴. 又∵,, ∴△AMN≌△AHN. ∴.························································· 5分 ∵,, ∴. ∴. ∴. ∴.···································· 6分 (3)由(1)知,,. 设,则,. ∵, ∴. 解这个方程,得,(舍去负根). ∴.························································································· 8分 ∴. 在(2)中,,, ∴.·········································································· 9分 设,则. ∴.即.···································································· 10分 |