A quadrilateral has:

·         four sides (also called edges),

·         four vertices (also called corners), and

·         its interior angles add up to 360 degrees.

There are special types of quadrilateral:

·         Rectangle, where all interior angles are 90? and opposite sides are equal.

·         Square, where all interior angles are 90? and all sides are equal. Square is a special type of rectangle.

·         Rhombus, where all sides are equal and opposite sides are parallel.

·         Parallelogram, where opposite sides are parallel and equal.

·         Trapezoid, where 2 sides are parallel.

Please note that rectangle, square, rhombus, parallelogram are all special types of trapezoid.

The area of a trapezoid is: area = base times height