Set a compass to draw a circle with a radius that's more than half the length of the line segment but less than the whole length. Put the compass point at one end of the segment and draw an arc above...
The perpendicular bisector of a line segment AB is the straight line perpendicular to AB through the midpoint of AB.
Only one.
One ! The word 'bisect' means to cut in two !
all three perpendicular bisectors elongate to meet at the incenter of the triangle.