PQ=QR ProvePR=QS ◄--------P-------Q----R--------S--------►

StatementsReasonsPQ=RS Given Q is between PR midpoint R is between QS midpoint PQ=QR QR=RS PQ+QR=QR+RS Segment Addition Postulate (Postulate 1.13) PR=PQ+QR and QS=QR+QS Segment Addition Postulate (Postulate 1.13) PR=QS Substitution Law (Postulate 1.11)