Dunkirk - Student Encyclopedia (Ages 11 and up) An important commercial seaport, Dunkirk lies in the extreme north of France on the Strait of Dover. In the evacuation of Dunkirk, one of the great actions of World War II, the town was demolished, but much of it had been rebuilt by 1953.
A line segment is a part of a line that is bounded by two distinct end points and contains every point on the line between its end points. Depending on how the line segment is defined, either of the two end points may or may not be part of the line segment.
trapezoid, closed plane figure bounded by four line segments, or sides, two of which are parallel and two of which are nonparallel. The parallel sides of a trapezoid are called bases and the nonparallel sides legs; in an isosceles trapezoid the legs are of equal length. The median of a trapezoid is the line segment connecting the midpoints of the legs; it is parallel to the bases and equal to half the sum of their lengths.