Because ∠ACB is a right angle and AC=BC.

So ∠CAB=∠CBA=45 degrees

So ∠EAB=∠EAD+∠DAB= 135 degrees.

Because ∠ACB is a right angle, DE⊥AC.

So BC‖DE

So ∠ EDB+∠ Abd =180-∠ CBA =135 degrees.

Because AD=BD

So ∠DAB=∠DBA

So ∠EAD=∠BDM

Because e = BMD = 90 degrees.

AD=BD

So △ AED △ BDM

So DE=BM=CE=CA+AE=CB+AE.

I hope you will adopt it! ! !