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.