Answer:
C
Step-by-step explanation:
Given that the triangles are congruent then corresponding sides are congruent.
YZ = BC = 12 and XZ = AC = 13, thus
cosZ = [tex]\frac{adjacent}{hypotenuse}[/tex] = [tex]\frac{YZ}{XZ}[/tex] = [tex]\frac{12}{13}[/tex]
