Question

A and B are respectively the points on the sides PQ and PR of a triangle PQR, such that
PQ=12.5 cm, PA=5 cm, and BR=6 cm. If AB parallel QR, find PR.

Answer 1

If AB||QR Then ∆PAB~∆PQR

According to Basic proportionate theorem (BPT)

PQ/PR=PA/PB

(PR=PB+BR)

12.5/PB+6=5/PB

12.5×PB=5(PB+6)

12.5PB=5PB+30

12.5PB-5PB=30

7.5PB=30

PB=30/7.5

PB=4

PR=PB+BR

PR=4+6

PR=10