Describe a process you would use to create the perpendicular bisector to a segment AB using only an unmarked straight edge and an unmarked compass.

1 answer

To create the perpendicular bisector of a segment AB using only an unmarked straight edge and an unmarked compass, you can follow the following process:

1. Begin by placing your straight edge vertically on the plane, ensuring that it spans the length of segment AB.
2. With the compass, open it to any arbitrary radius greater than half the length of segment AB. This will later be referred to as the "same radius".
3. Place the compass point on point A of segment AB and draw an arc that intersects the straight edge twice. Label these points of intersection as C and C'.
4. Without changing the radius of the compass, place the compass point on point B of segment AB and draw another arc that intersects the straight edge twice. Label these points of intersection as D and D'.
5. Draw straight lines connecting points C to D and C' to D'. These lines should intersect at a point, which we will label as E.
6. Now, using the compass, place the compass point on point E and adjust the compass leg to reach one of the points of intersection on the straight edge (C or C'). This sets the compass to the same radius as before.
7. Without changing the radius, place the compass point on one of the points of intersection (C or C') and draw an arc that intersects the other point of intersection on the straight edge.
8. Repeat step 7 but this time with the compass point on point E and the radius reaching the other point of intersection on the straight edge.
9. You should now have four points of intersection on the straight edge forming two segments. Connect these points to form a line that passes through point E. This line is the perpendicular bisector of segment AB as it intersects it at a 90-degree angle and divides it into two equal parts.

By following this step-by-step process, you can create the perpendicular bisector of a segment AB using only an unmarked straight edge and an unmarked compass.