A quadrilateral is a four-sided polygon. The interior angles of any quadrilateral add up to 360º. The quadrilaterals you should know are:

- Square – this has four sides of equal length and four equal (90º) angles. This means that it has two pairs of parallel sides.
- Rectangle – this has four equal (90º) angles and opposite sides of equal length. This has two pairs of parallel sides.
- Parallelogram – this has opposite sides of equal length. This has two pairs of parallel sides. This has two pairs of equal angles at opposite corners or vertices.
- Rhombus – this has four sides of equal length. This means that it has two pairs of parallel sides – so a rhombus is a special parallelogram; one with four equal sides.
- Trapezium – this has four sides, exactly two of which are parallel.
- Kite – this has two pairs of adjacent equal sides. This has one pair of equal angles at opposite vertices.

**Relevant lessons:**

- G1a – 2D geometry – terms and notation
- G1f – Drawing diagrams from a written description
- G3c – The sum of angles in a triangle and the angle properties of polygons
- G4a – Properties of special triangles and quadrilaterals
- G16a – Area of a rectangle
- G16b – Area of a triangle
- G16c – Area of a parallelogram
- G16d – Area of a trapezium
- G17a – Perimeter of polygons
- G17d – Perimeter and area of composite shapes made up of polygons
- G17e – Perimeter and area of composite shapes made up of polygons and sectors of circles