In the adjoining figure, ABCD and PQRC are rectangles, where Q is the midpoint of AC. Then DP is equal to
DP < PC
DP > PC
DP = PC
DP = 1/3 DC
CRQ = ∠CBA = 90o => QR || AB.
Therefore R is the midpoint of BC.
Similarly P is the midpoint of DC.
Therefore DP = PC.