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Congruent Line Segments
Definition: Line segments are congruent if they have the same length
Try this Adjust any line segment below by dragging an orange dot at its ends. The other line segments will change to remain congruent with it.
(If there is no image below, see support page.)

Line segments are congruent if they have the same length. However, they need not be parallel. They can be at any angle or orientation on the plane. In the figure above, there are three congruent line segments. Note they are laying at different angles. If you drag any of the six endpoints, the other segments will change length to remain congruent with the one you are changing.

For line segments, 'congruent' is similar to saying 'equals'. You could say "the length of line A equals the length of line B". But in geometry, the correct way to say it is "line segments A and B are congruent".

Rays and lines cannot be congruent because they do not have both end points defined, and so have no definite length.

Symbols
The symbol for congruence is congruence

Also, recall that the symbol for a line segment is a bar over two letters, so the statement
AB
 ≅  
PQ
is read as "The line segment AB is congruent to the line segment PQ".

Related topics

Congruent Triangles

Congruent Polygons

(C) 2008 Copyright John Page