ANSWER:
Definition of midpoint
SAS
Explanation:
WZ is divided into two segments by point Z, since Z is a midpoint, both segments are equal.
Therefore, the reason for the statement of WZ = YZ is the definition of midpoint.
Triangles VYZ and XWZ are congruent because previous statements established that they have two equal sides and one equal angle.
This means that they are congruent by SAS (side-angle-side)