Page 3 - LN

Step 4: Hold the ruler fixed. Slide the set-square along the ruler till the point P touches the other
arm of the set-square.

Step 5: Join PM along the edge through P, meeting l at M.

Conclusion: Therefore, PM is perpendicular to l.

Method-2: Using ruler and compasses
Step 1: Given a line l and a point P not on it.

Step 2: With P as centre, draw an arc which intersects line l at two points A and B.