###### Stuid
Updated on

A 2-dimensional geometrical figure which consists of ‘four’ sides is known as ‘quadrilateral’. It is derived from two words, ‘quad’ meaning ‘four’ and ‘lateral’ meaning side. Basically, a quadrilateral is closed and has a flat shape. The lines connect and it has straight sides.

• It is a polygon with four straight sides also known as edges.
• The four ‘vertices’ are also called ‘corners’.
• The four interior angles of a quadrilateral sums up to 360 degrees.

A polygon of 2D geometrical figure consisting of ‘four sides’ is called a quadrilateral. It is also known as:

• Quadrangle, which is derived from two words, namely quad meaning (four angles) and rangle which sounds like a “triangle”.
• Tetragon is derived from two words; gon sounds like hexagon, octagon etc.

## Parallelogram

A simple quadrilateral which falls under the Euclidean geometry, in a parallelogram both pairs of opposite sides are parallel to one another. A parallelogram has the following properties:

• Its opposite sides are congruent.
• Even the opposite angles will be in congruence.
• Adjacent angles will be supplementary (180 degree in measurement).
• Diagonals will intersect each other.

A rectangle is a type of parallelogram. Basically, all rectangles are parallelograms/quadrilaterals, since they have four right angles. On the other hand, all parallelograms and quadrilaterals are not rectangles.

A rectangle has the following properties:

• Opposite sides will be in congruence.
• Opposite angles will be in congruence.
• Adjacent angles will be supplementary.
• Diagonals will intersect each other, they will be in congruence as well.

A 2 dimensional, closed geometric object which consists of 4 equal sides is called a square. We can see ‘a square’ in our daily lives in the forms of wall clocks, chess boards etc.

A square has the following properties:

• It consists of 4 sides and 4 angles.
• Length of all sides are equal in measurement.
• Angles will measure 90 degrees (right angles).
• Interior angles will be equal in measurement, the sum of all interior angles will be equal  to  360°.

A square can also be called a rhombus (rectangle). To be specific, a parallelogram with 4 congruent sides and 4 right angles.

A rhombus is a type of parallelogram in which four sides will be in congruence to each other. The plural form of rhombus is ‘rhombi’. It consists of the following properties:

• Opposite sides of a rhombus will be congruent.
• Opposite angles will be in congruence.
• The adjacent angles will be supplementary (180 degrees).
• Diagonals will bisect each other at right angles.

A trapezoid is a unique kind of a quadrilateral which has exactly 1 pair of parallel sides. While they are called ‘trapezium’ in India and Britain; in America a trapezium is mostly a quadrilateral polygon with no parallel sides.

## Isosceles Trapezoid

A trapezoid in which non-parallel sides are in congruence to each other is known as an isosceles trapezoid. For example, most of the kites which consists of exactly two pairs of adjacent sides which are congruent are quadrilaterals.