
So all other quadrilaterals are irregular. The only regular (all sides equal and all angles equal) quadrilateral is a square. It has two diagonals that intersect each other at right angles. It's made up of two congruent triangles having a shared base. The Sum of adjacent angles of a parallelogram is equal to 180 degrees. It is a type of polygon having four sides (also called quadrilateral), where the pair of parallel sides are equal in length. Where two unequal sides are met, two angles are formed that are equal in measure. A parallelogram is a two-dimensional geometrical shape whose sides are parallel to each other. and that's it for the special quadrilaterals. A quadrilateral with two sets of equal-length sides that are adjacent to each other is called a kite. one of the diagonals bisects (cuts equally in half) the other.the diagonals, shown as dashed lines above, meet at.The KiteĮach pair is made of two equal-length sides that join up. (the US and UK definitions are swapped over!)Īn Isosceles trapezoid, as shown above, has left and right sides of equal length that join to the base at equal angles. NOTE: Squares, Rectangles and Rhombuses are allĪ trapezoid (called a trapezium in the UK) has a pair of opposite sides parallel.Īnd a trapezium (called a trapezoid in the UK) is a quadrilateral with NO parallel sides: Also opposite anglesĪre equal (angles "A" are the same, and angles "B"

The ParallelogramĪ parallelogram has opposite sides parallel and equal in length. In other words they "bisect" (cut in half) each other at right angles.Ī rhombus is sometimes called a rhomb or a diamond. The RhombusĪ rhombus is a four-sided shape where all sides have equal length (marked "s").Īlso opposite sides are parallel and opposite angles are equal.Īnother interesting thing is that the diagonals (dashed lines) meet in the middle at a right angle. The SquareĪ square has equal sides (marked "s") and every angle is a right angle (90°)Ī square also fits the definition of a rectangle (all angles are 90°), and a rhombus (all sides are equal length). The little squares in each corner mean "right angle"Ī rectangle is a four-sided shape where every angle is a right angle (90°).Īlso opposite sides are parallel and of equal length. Let us look at each type in turn: The Rectangle Some types are also included in the definition of other types! For example a square, rhombus and rectangle are also parallelograms. There are special types of quadrilateral:

They should add to 360° Types of Quadrilaterals Try drawing a quadrilateral, and measure the angles. interior angles that add to 360 degrees:.(Also see this on Interactive Quadrilaterals) Properties
