题目如图,Rt△ABCRt\triangle ABCRt△ABC中,∠B=30∘\angle B=30^{\circ}∠B=30∘,DDD是ABABAB边上一动点,把△ACD\triangle ACD△ACD沿直线CDCDCD折叠,点AAA落在点EEE处,当EDEDED平行于Rt△ABCRt\triangle ABCRt△ABC的直角边时,∠ADC\angle ADC∠ADC的度数为______.知识点:轴对称变换章节:图形的变化 / 图形的旋转