An isosceles trapezoid contains a single line of symmetry. A trapezoid is referred to as an isosceles trapezoid when its two non-parallel edges are equal in length.
In the United States, an enclosed two-dimensional quadrilateral figure that contains two opposite parallel segments is called a "trapezoid." The non-parallel sides are referred to as "legs," while the parallel segments are the "bases." In an isosceles trapezoid, the line of symmetry is formed when the trapezoid is divided into two equal parts such that one side exactly mirrors the other. This only occurs when the bisector is perpendicular to the bases. It should be noted that the British term for a trapezoid is a "trapezium."