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錎F2?E5?9B?69鏓BFC:y^2=4x,A(x1,y1)B(x2,y2)D(x3,y3)?2FC銭0A?64?9F?B9?16?84銭09?B9,銭14AF,BF,DF?10

题目详情
錎F2?E5?9B?69鏓BFC:y^2=4x,A(x1,y1)B(x2,y2)D(x3,y3)?
2FC銭0A?64?9F?B9?16?84銭09?B9,銭14AF,BF,DF?10
▼优质解答
答案和解析
AD的垂直平分线与X轴交于点E(3,0)时 AE = DE
(x1 - 3)^2 + y1^2 = (x3 - 3)^2 + y3^2
==== (x1-x3)(x1+x3 - 2) = 0 ==== x1 + x3 = 2\
|AF|,|BF|,|DF|成等差数列,
则,x2 = (x1+ x3) /2 = 1
y2 = 2 ,- 2
B坐标是(1,2)或(1,-2)