Draw a line and mark any point on it. Through this point construct a line perpendicular to by:
Using a ruler and compass
Steps of construction:
Step-1: Construct a line with point on it.
Step-2: Open the arm of the compass to a medium setting on the line .
Step-3: Without changing the compass setting draw an arc on the line at each side of the point forming points and .
These two points are thus at the same distance from .
Step-4: Put the compass pointer at , and set its width to any setting beyond .
Step-5: Draw an arc on one side of the line keeping pointer at .
Step-6: Without changing the setting of the compass place the pointer at and draw another arc so that two arcs intersect each other. Mark this point as .
Step-7: Using a ruler join and to get the required perpendicular.