挑战习题
1/5单选题
难度:

1.如图,在平面直角坐标系中,△ABC是直角三角形,∠ACB=90,AC=BC,OA=1,OC=4,抛物线y=x2-2x-3经过A,B两点,抛物线的顶点为D. 点E是直角三角形ABC斜边AB上一动点(点A、B除外),过点E作x轴的垂线交抛物线于点F,当线段EF的长度最大时,点E的坐标为(    )
A
B
C
D
提示1:
IOeUseebtOe6v0FC57uP6L+H54K5Qe+8iC0x77yMMO+8ie+8jELvvIg077yMNe+8ie+8jOWNs+WPr+axguW+l+ebtOe6v0FC55qE6Kej5p6Q5byP77yM5Y+I55Sx5LqM5qyh5Ye95pWweT14PHN1cD4yPC9zdXA+LTJ4LTPvvIzorr7ngrlF77yIdO+8jHQrMe+8ie+8jOWImeWPr+W+l+eCuUbnmoTlnZDmoIfvvIzliJnlj6/msYLlvpdFRueahOacgOWkp+WAvO+8jOaxguW+l+eCuUXnmoTlnZDmoIfvvJs=
正确答案:QQ==
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