在比例图中，PQRS 代表一片用于建公园的土地。 比例尺：1 cm 代表 0.5 km

1. Construct the angle bisector of $\angle PQR$ using standard compass arcs.

With centre $Q$, draw an arc cutting $QP$ and $QR$ at two points.
Using the same compass radius from these two points, draw two arcs inside $\angle PQR$ so that they intersect.
Draw a straight line from $Q$ through the intersection of the two arcs. This line is the angle bisector of $\angle PQR$.

1. Construct the perpendicular bisector of $RS$ using equal-radius compass arcs.

Set the compass radius to more than half of $RS$. With centre $R$, draw arcs above and below $RS$. Using the same radius and centre $S$, draw arcs to intersect the first pair of arcs. Draw a straight line through the two arc-intersection points. This line is the perpendicular bisector of $RS$.

1. Identify and mark a point satisfying both locus conditions.

Since $F$ is equidistant from $PQ$ and $QR$, $F$ must lie on the angle bisector of $\angle PQR$.

Since $F$ is nearer to $R$ than to $S$, $F$ must be on the same side of the perpendicular bisector of $RS$ as $R$.

Choose any point inside the park $PQRS$ that lies on the angle bisector of $\angle PQR$ and is on the $R$-side of the perpendicular bisector of $RS$. Label this point $F$.