We are given side BC equals to side CE and angle CBA equals to angle CED We also know that angle ACB equals to angle ECD are equal (opposite angles properties)
We have enough information to deduce that triangle ABC and triangle CDE are equal by postulate Angle-Side-Angle (ASA)
We are given side AB equal to side ED, side BC equals to side EF, and side AC equals to side DF We have enough information to deduce that triangle ABC and triangle DEF congruent by postulate Side-Side-Side (SSS)