20 1 1 Find the answer to the last multiple-choice question in Yiwu senior high school entrance examination.

Answer: ∵ Quadrilateral AEDC is a parallelogram

∴ED=AC,AE=CD

∫△ADE and △ABC are isosceles right triangles.

∴AE=AD=CD,AB=AC=DE

∴AD？ +CD？ =AC？

∴△ACD is an isosceles right triangle

So △ CDE △ is not good

∴CE=BD

∫∩BAD =∩BAE

∴△ABD≌△ABE

Therefore, ADB =∩AEB.

∫△ACE?△ABD

So ∩ bad =∩ACE

∴∩BGC=90 =∩CGD

Because ∩AEF=∩GCD.

∴△AEF∽△GCD

∴CD/EF=CG/AC

That is CD*AE=EF*CG.

So choose d