Isosceles trapezoid

Isosceles trapezoid
Isosceles trapezoid with axis of symmetry
Type	quadrilateral, trapezoid
Edges and vertices	4
Symmetry group	Dih1, [ ], (*), order 1
Properties	convex, cyclic
Dual polygon	Kite

In Euclidean geometry, an isosceles trapezoid (isosceles trapezium in British English) is a convex quadrilateral with a line of symmetry bisecting one pair of opposite sides. It is a special case of a trapezoid. Alternatively, it can be defined as a trapezoid in which both legs and both base angles are of equal measure,^[1] or as a trapezoid whose diagonals have equal length.^[2] Note that a non-rectangular parallelogram is not an isosceles trapezoid because of the second condition, or because it has no line of symmetry. In any isosceles trapezoid, two opposite sides (the bases) are parallel, and the two other sides (the legs) are of equal length (properties shared with the parallelogram), and the diagonals have equal length. The base angles of an isosceles trapezoid are equal in measure (there are in fact two pairs of equal base angles, where one base angle is the supplementary angle of a base angle at the other base).