
How to construct a line perpendicular to a given line, passing through a given point not on this line?

1. 
 Start with two points defining the given line.


2. 
 Determine the given point.


3. 
 Draw an arc with its center at point 2 and a suitable radius. The arc must intersect line 1 twice at points with a suitable distance.


4. 
 Draw an arc with its center at one of the intersections of line 1 and arc 3, with a suitable radius.


5. 
 Repeat this for the other intersection. The radius must be equal to that of arc 4, and both arcs must intersect at the opposite side of line 1 relative to point 2.


6. 
 Draw the line connecting point 2 to the intersection of arcs 4 and 5.


7. 
 The part of line 6 from point 2 to the intersection of it with line 1 is the line to be constructed, perpendicular to line 1 and passing through point 2.

