The angles in a add up to .

The properties of different kinds of quadrilaterals are listed below.

Square

a square is the only regular quadrilateral

all angles are equal

all sides are of equal length

opposite sides are parallel

the diagonals bisect each other at

the diagonals are equal in length

Rhombus

with a rhombus, all sides are of equal length

opposite sides are parallel

diagonally opposite angles are equal

the diagonals bisect each other at

Rectangle

with a rectangle, all angles are equal

opposite sides are of equal length

the diagonals are equal in length

opposite sides are parallel

the diagonals bisect each other

Parallelogram

with a parallelogram, diagonally opposite angles are equal

opposite sides are of equal length

opposite sides are parallel

the diagonals bisect each other

Trapezium

with a trapezium, one pair of opposite sides is parallel

Kite

with a kite, two pairs of sides are of equal length

one pair of diagonally opposite angles is equal

only one diagonal is bisected by the other

the diagonals cross at

Other 2D shapes are considered in the study guide on polygons and circles.