4. determine whether the following definition is reversible. if it is, write the definition as a bi-conditional. two angles that are congruent have equal measures.

It can be written. You have to write the converse and conditional first.
Conditional: if two angles are congruent, then they have the same measure.
Converse: if two angles have the same measure, then they are congruent.

Both these statement have to be correct or write a biconditional.
Biconditional: two angles are congruent if and only if they have equal measures.