To prove: PR || DF.
Construction : Join PR.
Proof: In ∆XED, we have PQ || DE.
Therefore, by using Basic proportionality theorem, we have
...(i)
In ∆XEF, we have
QR || EF
Therefore, by using Basic proportionality theorem, we get
Comp. (i) and (ii), we get
Therefore, by the converse of Basic proportionality theorem, we get
PR || DF Hence proved.