x = 23
Explanation:
Given: triangle ABC and triangle DEF
we need to find the triangle congruency theorem in order to determine the value of x.
AB = DE
AC = DF
∠A = ∠D
the sides BC and EF respectively were not marked.
Since, we were not given the value of the angles but we know they are equal. And two sides of triangle ABC and the corresponding two sides of triangle DEF were given. It means BC is equal to EF.
The sides opposite ∠A = BC
The sides opposite ∠D = EF
BC = EF
x - 4 = 19
collect like terms:
x = 19 + 4
x = 23
