Help ASAP. EXPLAIN AND WORK IT OUT. Tell me which formula you used to solve the problem? # 8

Answer:
number 8 is a square
Step-by-step explanation:
Q and R share the same x coordinate, it forms a segment perpendicular to x axis
S and T has the same perpendicular to x axis
while (T and R) (s and Q) perpendicular to y axis
TR = SQ = 4
ST = QR = 4