∴AE2+EF2=AF2，∴∠AEF=90°
∴∠AEB+∠FEC=90°
∵正方形ABCD
∴∠ABE=∠FCE=90°
∵∠CFE+∠CEF=∠EAB+∠AEB=90°
∴∠FEC=∠EAB
∴△ABE∽△ECF
∴EC：AB=EF：AE=3：4，即EC=
| 3 |
| 4 |
| 3 |
| 4 |
∴BE=
| BC |
| 4 |
| AB |
| 4 |
∵AB2+BE2=AE2，∴AB2+
| AB2 |
| 16 |
| 162 |
| 17 |
∴正方形ABCD面积=AB2=
| 256 |
| 17 |
故选C．
A. | 225 |
| 16 |
| 256 |
| 15 |
| 256 |
| 17 |
| 289 |
| 16 |
| 3 |
| 4 |
| 3 |
| 4 |
| BC |
| 4 |
| AB |
| 4 |
| AB2 |
| 16 |
| 162 |
| 17 |
| 256 |
| 17 |