$解:(1)∠BCE与∠BAC相等或互补,理由如下:$
$当D在线段BC上时,如图1(a)$
$由题,AD=AE$
$∵∠DAE=∠BAC,∴∠BAD=∠CAE$
$在△ABD和△ACE中$
${{\begin{cases} {{AB=AC}} \\ {∠BAD=∠CAE} \\ {AD=AE} \end{cases}}}$
$∴△ABD≌△ACE(SAS)$
$∴∠ABC=∠ACE$
$∴∠BCE=∠BCA+∠ACE=∠BCA+∠ABC$
$而∠BAC+∠BCA+∠ABC=180°$
$∴∠BCE+∠ABC=180°$
$当D在BC延长线上时,如图1(b)$
$同理可证△ABD≌△ACE,∴∠ABD=∠ACE$
$∴∠BCE+∠ABC=180°$
$当D在CB延长线上时,如图1(c)$
$同理可证△ABD≌△ACE,∴∠ABD=∠ACE$
$∵∠ABD=∠BAC+∠ACB,∠ACE=∠ACB+∠BCE$
$∴∠BCE=∠BAC$
$(2)（更多请点击查看作业精灵详解）$
