解:(1)等腰直角三角形;等腰梯形(答出三角形,梯形也给分).······· (2分)
(2)等腰直角三角形

在整个移动过程中与等腰梯形

重叠部分图形的形状可分为以下两种情况:

①当

时,重叠部分的形状为等腰直角三角形

(如图①).············ (3分)
此时

,过点

作

于点

,则

平分

,

,········································································ (4分)

.············································ (6分)
②当

时,重叠部分的形状是等腰梯形

(如图②).················· (7分)
此时,

,

,

,

四边形

是平行四边形,

,

.·································································· (8分)
过点

作

于

,过点

作

于

,
则

,··············································· (9分)

.··················· (10分)
(3)当等腰直角三角形

移动到

边经过点

时,移动时间为

,

当

时,

.

当

时,等腰直角三角形

与等腰梯形

重叠部分的面积是

.(12分)解析:
略