As a result of this definition:
- Each pair of opposite sides is of equal length.
- Opposite sides are parallel
- Diagonals are equal
- Adjacent sides are perpendicular
- Area = product of any two adjacent sides
- There are many definitions of rectangle, but it seems sensible to use one which is based on angle properties rather than length or parallelism properties. Definition adapted from http://www.mathsisfun.com/definitions/rectangle.html