In the adjoining figure, the side AC of ∆ABC is produced to E such that CE = 1/2 AC. If D is the midpoint of BC and ED produced meets AB at F, and CP, DQ are drawn parallel to BA, then FD is
FD = 1/3 FE
In ∆ABC, D is the midpoint of BC and DQ || BA.
Therefore Q is the midpoint of AC.
Therefore AQ = AC.
Now FA || DQ || PC, and AQC is the transversal such that AQ = QC and FDP is the other transversal on them.
Therefore FD = DP (i) [by intercept theorem]
Now EC = 1/2 AC = QC.
Therefore in ∆EQD, C is the midpoint of EQ and CP || DQ.
Therefore P must be the midpoint of DE.
Therefore DP = PE (ii)
Thus FD = DP = PE [from (i) and (ii)]
Hence FD = 1/3 FE.