AD = BD .....on perpendicular bisector of AB
Triangle DBC is congruent to triangle DAE .... SSS
Angle DCB=Angle DEA .... corresponding parts of congruent triangles
Angle DEC=Angle DCE ..... base angles of an isosceles triangle
Angle ECB = Angle CEA .... subtraction
Triangle ECB is congruent to triangle CEA .... SAS
AC=BE... corresponding parts of congruent triangles.