ΔECD≡ΔECB (LUL, DC≡CB, EC≡EC, m∡ECD=m∡ECB=180°-45°=135°)
⇒EB≡ED⇒ΔDEB isosel de baza DB
CD≡CB, dar si ED≡EB⇒EC mediatoare,ΔDEB isoscel, EC bisectoare
dar ΔECD si ΔECB isoscele de baze SE si ,respectivBE
deci m∡BEC=m∡DEC=(180-135)/2=45°/2⇒m∡DEB=45°
⇒m∡EBD=m∡EDB=(180-45)°/2=135°/2=67°30'
grea!