(1) Let \(\over{AB}\) be the given line segment.
(2) Adjust the compasses up to the length of \(\over{AB}\)
(3) Draw any line 1 and mark a point P on it.
(4) Put the pointer on P and without changing the setting of compasses, draw an arc to cut the line segment at point X.
(5) Now, put the pointer on point X and again draw an arc with the same radius as before, to cut the line 1 at point Q.
\(\over{PQ}\) is the required line segment.