AE=6
设AE=x
AE=BE=x ,AD=DB=BC EC=ED AC=9
BC^2=BE^2-EC^2=x^2-(9-x)^2
AB^2=(2AD)^2=4AD^2=4[x^2-(9-x)^2]
AB^2=BC^2+AC^2 4[x^2-(9-x)^2]=x^2-(9-x)^2+81
解得x=6
AE=6
设AE=x
AE=BE=x ,AD=DB=BC EC=ED AC=9
BC^2=BE^2-EC^2=x^2-(9-x)^2
AB^2=(2AD)^2=4AD^2=4[x^2-(9-x)^2]
AB^2=BC^2+AC^2 4[x^2-(9-x)^2]=x^2-(9-x)^2+81
解得x=6