Draw any line segment ¯¯¯¯¯¯¯¯AB. Mark any point M on it. Through M, draw a perpendicular to ¯¯¯¯¯¯¯¯AB. (Use ruler and compasses)
Steps of construction:
(i) Draw a line segment ¯¯¯¯¯¯¯¯AB of any length and mark a point M on it.
(ii) With M as the center and a convenient radius, draw an arc intersecting the line AB at two points C and B.
(iii) With C and D as center and a radius greater than MC, draw two arcs, which cut each other at P.
(iv) Join PM. Then PM is perpendicular to AB through point M.