Step-by-step explanation:
1. Choose arbitrary points A and B in the plane and draw segment AB.
2. Raise a perpendicular m to AB at A.
3. Raise a perpendicular n to AB at B.
4. Choose an arbitrary point C on line n.
5. Drop a perpendicular from point C to line m. Let D be the foot of this perpendicular.
6. Then quadrilateral ABCD is a rectangle.
