Describe how a geometry app can divide segment \(\overline{AB}\) into five congruent parts by creating a family of parallel lines. Explain why the five parts are equal.

Hints
- Create equal reference intervals on a ray from one endpoint.
- Connect the last reference point to the other endpoint of the segment.
- Use parallel lines to transfer the equal spacing to \(\overline{AB}\).
Solution
1. The app creates an auxiliary ray from \(A\) that is not collinear with \(\overline{AB}\).
2. Using one fixed length, the app marks five consecutive congruent segments on the ray, ending at points \(P_1,P_2,P_3,P_4,P_5\).
3. The app draws \(\overline{P_5B}\).
4. Through each of \(P_1,P_2,P_3,P_4\), the app creates a line parallel to \(\overline{P_5B}\). Let these lines meet \(\overline{AB}\) at \(Q_1,Q_2,Q_3,Q_4\).
5. Parallel lines cut transversals proportionally. Since the five segments on the auxiliary ray are congruent, the corresponding segments \(AQ_1\), \(Q_1Q_2\), \(Q_2Q_3\), \(Q_3Q_4\), and \(Q_4B\) are congruent.
Answer
The app marks five equal steps on an auxiliary ray from \(A\), connects the fifth point to \(B\), and creates parallels through the first four marked points. Their intersections divide \(\overline{AB}\) into five congruent parts by the proportional-segments theorem.