# What quadrilaterals have four sides of equal length that meet

Learn about and revise angles, lines and multi-sided shapes and their properties with this BBC Bitesize GCSE Maths Edexcel study guide. Quadrilateral is a geometric shape that consists of four points (vertices) which means that the four sides of the quadrilateral only meet at the vertices, two at A trapezoid, in which the non-parallel sides are equal in length, is called isosceles. In Euclidean plane geometry, a quadrilateral is a polygon with four edges (or sides) and four Square (regular quadrilateral): all four sides are of equal length (equilateral), and all four angles are right angles. An equivalent An equilic quadrilateral has two opposite equal sides that, when extended, meet at 60°. A Watt.

Imagine extending the pairs of opposite sides. They would never intersect because they are parallel. Notice, also, that the opposite angles of a parallelogram are congruent, as are the opposite sides.

The parallel sides are also the same length: These relationships are true for all parallelograms. There are two special cases of parallelograms that will be familiar to you from your earliest experiences with geometric shapes. The first special case is called a rectangle. By definition, a rectangle is a parallelogram because its pairs of opposite sides are parallel.

A rectangle also has the special characteristic that all of its angles are right angles; all four of its angles are congruent. The other special case of a parallelogram is a special type of rectangle, a square. A square is one of the most basic geometric shapes.

• Angles, lines and polygons

It is a special case of a parallelogram that has four congruent sides and four right angles. Rectangles include squares and oblongs.

An equivalent condition is that opposite sides are parallel a square is a parallelogramthat the diagonals perpendicularly bisect each other, and are of equal length. A quadrilateral is a square if and only if it is both a rhombus and a rectangle four equal sides and four equal angles.

This implies that one diagonal divides the kite into congruent trianglesand so the angles between the two pairs of equal sides are equal in measure. It also implies that the diagonals are perpendicular. A convex quadrilateral is tangential if and only if opposite sides have equal sums.

It is a type of cyclic quadrilateral. A Watt quadrilateral is a quadrilateral with a pair of opposite sides of equal length.

The point of intersection of the sides is not considered a vertex of the quadrilateral. The shapes of elementary geometry are invariably convex.