51281410
Segment \(\overline{AB}\) has length \(7.6\,\text{cm}\).
a) Describe a compass-and-straightedge procedure for locating its perpendicular bisector.
b) Give the length of each of the two parts of \(\overline{AB}\).
c) What special property does every point on the perpendicular bisector have in relation to \(A\) and \(B\)?
Hints
- How large must the compass radius be for the arcs to intersect twice?
- Where does a perpendicular bisector cross the original segment?
- Compare the distances from any point on the perpendicular bisector to the endpoints.
Solution
1. Draw \(\overline{AB}=7.6\,\text{cm}\).
2. Open the compass to a radius greater than \(3.8\,\text{cm}\). With center \(A\), draw arcs above and below the segment. Without changing the compass width, repeat with center \(B\).
3. Draw the line through the two arc intersection points. This line is the perpendicular bisector of \(\overline{AB}\).
4. The midpoint divides the segment into two parts of length \(7.6\div2=3.8\,\text{cm}\).
5. Every point on the perpendicular bisector is equidistant from \(A\) and \(B\).
Answer
a) Draw equal-radius arcs from \(A\) and \(B\) with radius greater than \(3.8\,\text{cm}\), then draw the line through their two intersections.
b) Each part is \(3.8\,\text{cm}\).
c) Every point on the perpendicular bisector is the same distance from \(A\) as from \(B\).
