In known triangle ABC, angle ACB is equal to 90 degrees, AC is equal to BC, ad is vertical to CE, be is vertical to CE, D and E are perpendicular feet

In known triangle ABC, angle ACB is equal to 90 degrees, AC is equal to BC, ad is vertical to CE, be is vertical to CE, D and E are perpendicular feet

There are no pictures. I have to give you the process according to the picture I drew
(mainly to prove the congruence of triangle ACD and triangle BCE)
Angle ACD + angle BCE = 90 degrees
Angle CBE + angle BCE = 90 degrees
So: angle ACD = angle CBE (the remainder of the same angle is equal)
Angle e = angle ADC = 90 degrees
AC=BC
Triangle ACD and triangle BCE congruence (AAS)
So CD = be
So de + be = de + CD = CE