Question

which part of the figures must be checked to confirm congruence?
only the sides
only the angles
all corresponding sides and angles
only the perimeter

Explanation:

Congruent figures have the same shape and size. This means all corresponding sides and angles must be equal. Checking only sides (could have same sides but different angles), only angles (could have same angles but different side lengths), or only perimeter (perimeter can be same with different side - angle combinations) is insufficient.

Answer:

All corresponding sides and angles