This page shows how to copy a line segment with compass and straightedge or ruler. Given a line segment, this shows how to make another segment of the same length.
The above animation is available as a printable step-by-step instruction sheet, which can be used for making handouts or when a computer is not available.
The proof of this construction is trivial. Refer to the figure above in step 8.
|1||All points along the the arc S are the same distance from R||R is the center of the arc. See Arc definition|
|2||This distance is equal to the length of segment PQ||The arc was drawn with that compass width|
|3||RS is congruent to PQ||S is a point on the arc. See (1).|