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) |