Constructions with a single compass

A single compass construction is a geometric construction where only a compass (and not a straightedge) is used. Surprisingly, any construction that can be done with a compass and straightedge can also be done with a compass alone, though the steps may be more complex.

Important properties

• A compass can be used to transfer distances and draw circles.

• Using only a compass, you can find intersection points, copy segments, and construct midpoints.

• The straightedge is not needed for the actual construction, but points and circles can still be marked.