Answer:
Perpendicular bisector theorem
Step-by-step explanation:
Perpendicular bisector theorem: if a point is on the perpendicular bisector of a segment, then it is equidistant from the segment's endpoints.
So, if segment ST is the perpendicular bisector of segment RV, then, by perpendicular bisector theorem, any point in segment ST (like S) is equidistant from points R and V, in consequence, segments RS and SV are equal.
