A pair of perpendicular line segments is not shown. among the pictures you've submitted.
http://wiki.answers.com/Q/Which_picture_shows_a_pa...

1. Set the width of a compass so that it is about 3/4 of the length of the segment that you want to bisect. 2. Place the compass point on one of the endpoints, and draw two arcs on
http://www.ehow.com/how_8692739_bisectlinesegmen...

1 Understand the midpoint. The midpoint of a line segment is the point that is located on the exact midpoint of the two endpoints. Therefore, it's the average of the two endpoints
http://www.wikihow.com/FindtheMidpointofaLine...
