To find the perpendicular bisector you first need to create a line segment. Now mark both end of the segment A and B. Next mark a point on the line AB this is now point C. Now use the compass tool and create a circle using point C and point A. Drag the circle over to the center of pointy A. Complete that step a second time using the compass to make a circle from point A and C. Drag the new circle onto point B. Then mark the intersection of the two circles with points D and E. You now know this is a perpendicular bisector because there are 4 90 degree angles. This process is also how you find the midpoint on a line this is where the vertical line crosses with the horizontal. You know point F is the midpoint because you measured 2.51 on either side of point F.