在比例图中，城镇 W、X 和 Y 如下所示。城镇 Z 距离城镇 W 10 cm，距离城镇 Y 8 cm。

1. Locate the possible position of Z using the given distance from W.

Set the compass to $10\text{ cm}$. With centre $W$, draw an arc/circle representing all points $10\text{ cm}$ from $W$.

2. Use the distance from Y to fix Z and complete the quadrilateral.

Set the compass to $8\text{ cm}$. With centre $Y$, draw an arc/circle to intersect the first arc/circle at $Z$. Mark the required intersection as $Z$, then join $Z$ to $W$ and $Z$ to $Y$ to complete quadrilateral $WXYZ$.

1. Draw equal-radius arcs from $X$ and $Y$ to locate two points equidistant from $X$ and $Y$.

Set the compass radius to more than half of $XY$. With centre $X$, draw arcs above and below $XY$. Using the same radius and centre $Y$, draw arcs to intersect the first pair of arcs at two points.

2. Join the two arc-intersection points to form the perpendicular bisector of $XY$.

Draw a straight line through the two arc-intersection points. This line is the perpendicular bisector of $XY$, meeting $XY$ at its midpoint and at right angles.

1. Construct equal-distance points on the two arms of the angle and use them to locate the bisector.

With centre $X$, draw an arc cutting $XW$ and $XY$ at two points. Using these two points as centres and the same radius, draw arcs intersecting inside $\angle WXY$. Join $X$ to this intersection point. This line is the angle bisector of $\angle WXY$.