<h3>Answer: Always</h3>
Explanation:
Drawing out a diagram usually helps with these types of problem. See the diagram below.
We have angle 3 and angle 4 as corresponding angles (since they are both in the north east corner of each four-corner configuration). Angle 1 = angle 3 is one pair of vertical angles and angle 2 = angle 4 is another pair of vertical angles. We see that angles 1 and 2 are corresponding angles in the south west corners of each four-corner configuration. That's why the original statement is always true.