Final answer:
Without a proper context or diagram, there is insufficient information to determine the measure of angle mBD in triangle ZBC based on the angles mEF and mZACD provided.
Step-by-step explanation:
To determine the measure of angle mBD in triangle ZBC, given that mEF = 45° and mZACD = 56°, we would need to establish the relationship between these angles and angle mBD. Unfortunately, the information provided is not directly related to triangle ZBC, and the angles mEF and mZACD do not seem to refer to angles within triangle ZBC based on typical geometric notation.
Furthermore, without a diagram or additional information regarding how angles mEF and mZACD relate to triangle ZBC, it is impossible to accurately determine the measure of angle mBD. Therefore, we cannot answer the student's question without more context or a correct description of the problem.