Answer:
AC
Step-by-step explanation:
AC is the common angle to both ∆ABC and ∆CDA in the geometry question presented.
When asked to identify the side or angle that is common to ∆ABC and ∆CDA, we look for a geometric component that both triangles share. By examining the labels of the triangles, it becomes clear that angle C is part of both ∆ABC and ∆CDA. Thus, angle C is the common angle to both triangles. Additionally, in triangle problems, it is common to be asked for measurements of sides or angles, which may involve using tools like a protractor or applying geometric principles.
