Construction of a Square
1. Construct a line segment. 2. Construct a perpendicular line from a point on the line segment. 3. Draw a circle with one point as the center and the other point as a point on the circle arc. 4. Mark the intersection of the perpendicular line and circle. 5. Construct a line parallel to the original segment. 6. Construct a perpendicular line from the other point on the line segment.