Properties of Congruence

For all angles $A$ , $\angle A\cong \angle A$ .

An angle is congruent to itself.

For any angles $A\text{and}B$ ,

if $\angle A\cong \angle B$ , then $\angle B\cong \angle A$ .

Order of congruence does not matter.

For any angles $A,B,\text{and}C$ ,

if $\angle A\cong \angle B$ and $\angle B\cong \angle C$ , then $\angle A\cong \angle C$ .

If two angles are both congruent to a third angle, then the first two angles are also congruent.