
Given: In ΔPQR, S and T are points on sides PR and QR
To Prove: ΔRPQ ~ ΔRTS
Proof: In ∆RPQ and ∆RST,
\(\angle\)RTS = \(\angle\)QPS (Given)
\(\angle\)R = \(\angle\)R (Common angle)
∴ ∆RPQ ∼ ∆RTS (By AA similarity criterion)
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 \( BC = 3.6 \, \text{cm} \).