Draw a right angle? Nothing is easier with a compass!
- Draw an AB segment on the chosen support and locate its center O.
- Set the compass spacing along the length of this segment.
- Prick the compass in A and draw an arc of the circle above the center O.
- Then prick the compass in B and draw another arc.
- Then connect the center O and the intersection of the two arcs. This segment is perpendicular to the AB axis.