Question

construct the midpoint of ab.

Explanation:

Step1: Use compass and straight - edge

1. Place the compass at point A.
2. Open the compass to a radius greater than half the length of AB.
3. Draw arcs above and below the line segment AB.

Step2: Repeat with compass at point B

1. Place the compass at point B.
2. Using the same radius as in Step 1, draw arcs above and below the line segment AB, intersecting the arcs drawn from point A.

Step3: Draw the perpendicular bisector

1. Use a straight - edge to draw a line connecting the two intersection points of the arcs.
2. The point where this line intersects AB is the mid - point of AB.

Answer:

The mid - point is the intersection of the perpendicular bisector and line segment AB.