So CE=AD and BD=AE.

Because AD+DE=AE

So AD+DE=BD

Because CE=AD

So CE+DE=BD

(2)△ABD is a right triangle, ∠ ADB = 90.

Proof: Because △BAD and △ACE are identical, ∠ ADB = 90.

So ∠ ADB =∠ CEA = 90.

Because ADB = 90.

So ∠ BDE = 90.

So ∠ BDE = ∠ CEA = 90.

So BD is parallel to CE.