Learn about the properties of isosceles trapezoids including relationships among opposite sides, opposite angles, adjacent angles, diagonals and angles formed by diagonals.
Isosceles Trapezoid: A trapezoid with one pair of parallel lines and the non-parallel sides congruent.
Isosceles trapezoids are special types of trapezoids that have the pair of of non-parallel legs being congruent to each other. This means that the trapezoid appears symmetrical, and that the diagonals are equal in length.
Like an isosceles triangle, isosceles trapezoids have base angles that are congruent. This means that the two smaller angles are congruent to each other, and the two larger angles are congruent to each other.
When diagonals are drawn, the still do not bisect each other. The bottom part of the two diagonals are congruent to each other, and the top part of the two diagonals are also congruent to each other.
An isosceles trapezoid also has two of the opposite triangles formed by the diagonals that are similar to each other, meaning all their sides and angles are in proportion. The other two opposite triangles formed are congruent to each other by side-side-side.