
Consider the figure in which PQ is a line segment joining the mid-points P and Q of line AB and AC respectively.
i.e., AP = PB and AQ = QC
It can be observed that
\(\frac{AP}{PB}=\frac{1}{1}\) and \(\frac{AP}{PB}=\frac{1}{1}\)
∴\(\frac{AP}{PB}=\frac{AQ}{QC}\)
Hence, by using the basic proportionality theorem, we obtain
PQ || BC
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 \( BC = 3.6 \, \text{cm} \).