Answer:
Option A is correct.
The missing justification is: Transitive property
Step-by-step explanation:
Given: [tex]\angle A \cong \angle B[/tex] , [tex]\angle C \cong \angle B[/tex]
Symmetric property of equality states the if for all real values of x , y
if x =y then, y =x.
Then, by symmetric property of equality:
we can write [tex]\angle C \cong \angle B[/tex] as
[tex]\angle B \cong \angle C[/tex]
Transitive property of equality states that if we have the two things that are equal to each other and the second thing is equal to a third thing.
i.e, if a =b and b =c
then a =c
By transitive property of equality:
if [tex]\angle A \cong \angle B[/tex] and [tex]\angle B \cong \angle C[/tex]
then;
[tex]\angle A \cong \angle C[/tex] ......[1]
Congruent angle states that the angles have exact the same measure
Therefore, by definition of congruent angles in [1] we have;
[tex]m\angle A = m \angle C[/tex]