we know that
In a triangle, a median is created by a vertex connected to the midpoint of the opposite side. Where all three lines intersect is the centroid, which is also the "center of mass"
In this problem
In the triangle TRS, the point Z is the centroid
The property of the centroid states that
Find the value of RV
we have
so
Find the value of RZ
therefore
the answer is
RZ is