Constructions using a two-sided straightedge

A two-sided straightedge is a tool similar to a regular straightedge, but both of its edges can be used simultaneously for drawing or aligning. Constructions using a two-sided straightedge allow you to perform geometric constructions that are not possible with a standard straightedge and compass. For example, you might use both sides to transfer distances or create parallel lines in a single move.

Important properties

• A two-sided straightedge can be placed so that both edges touch different points or lines at the same time.

• It allows constructions such as drawing a line through a point parallel to a given line, or copying a segment length to another location, without a compass.

• Some constructions that are impossible with compass and straightedge alone become possible with a two-sided straightedge.