
Given: \(\frac{QR}{QS}=\frac{QT}{PR}\) and \(\angle 1 =\angle 2\)
To Prove: ΔPQR∼ΔTQR
Proof: In ∆PQR,
\(\angle\)PQR = \(\angle\)PRQ
∴ PQ = PR ………………(i)
Using (i) we obtain
\(\frac{QR}{QS}=\frac{QT}{QP}\).............(ii)
In ΔPQS and ΔTQR,
\(\frac{QR}{QS}=\frac{QT}{QP}\) [using (ii)]
\(\angle\)Q=\(\angle\)Q
∴ ΔPQS∼ΔTQR
Hence Proved

In the adjoining figure, \( AP = 1 \, \text{cm}, \ BP = 2 \, \text{cm}, \ AQ = 1.5 \, \text{cm}, \ AC = 4.5 \, \text{cm} \) Prove that \( \triangle APQ \sim \triangle ABC \).
Hence, find the length of \( PQ \), if \( BC = 3.6 \, \text{cm} \).