Finding the bisect
To find the bisect of a line you have two choices;
Example 1
Use a protractor.
Find the bisect of the following line
Find the half way point between A & B.
Now use a protractor to place a point 90° to the line `A-B`.
Draw a line from the half way point to the 90° point.
This is now a perpendicular bisect of these two points.
Example 2
Use a pencil compass.
Find the bisect of the following line.
Find the half way point between A & B.
Now use a pencil compass that is open more than half way on each point A & B.
Now join the two arc intersections.
This is now the perpendicular bisect of A & B.