Constructing Perpendicular Lines

How to construct perpendicular lines using a compass and a straight edge.

Draw a line with your straight edge and put two points on them. Label one A and the other one B.

Draw an arch with your compass on B to the right.

Draw an arch with your compass on B to the left.

Draw an arch with your compass on A to the left. It should intersect with the arch you drew to the left on B.

Draw an arch with your compass on A to the right. It should intersect with the arch you drew to the right on B.

Connect the two intersection of the archs to create perpendicular lines.