( 1 )画出格点△ABC关于直线DE的对称的△A1B1C1;
( 2 )在DE上画出点P,使PA+PC最小;
( 3 )在DE上画出点Q,使QA﹣QB最大.
平面直角坐标系xOy中,点A,B的坐标分别是(-3,1),(-1,4),