Printable instructions for drawing a perpendicular at a point on a line with compass and straightedge or ruler

Constructing perpendicular at a point on a line

This is the step-by-step, printable version. If you PRINT this page, any ads will not be printed.

See also the animated version.

	After doing this	Your work should look like this
	Start with a line and point K on that line.
1	Set the compasses' width to a medium setting. The actual width does not matter.
2	Without changing the compasses' width, mark a short arc on the line at each side of the point K, forming the points P,Q. These two points are thus the same distance from K.
3	Increase the compasses to almost double the width (again the exact setting is not important).
4	From P, mark off a short arc above K
5	Without changing the compasses' width repeat from the point Q so that the the two arcs cross each other, creating the point R
6	Using the straight edge, draw a line from K to where the arcs cross.
7	Done. The line just drawn is a perpendicular to the line at K

After doing this

Your work should look like this

Start with a line and point K on that line.

Set the compasses' width to a medium setting. The actual width does not matter.

Geometry construction with compass and straightedge or ruler or ruler

Without changing the compasses' width, mark a short arc on the line at each side of the point K, forming the points P,Q. These two points are thus the same distance from K.