A rectangle is a parallelogram with four right angles.


Because it is a parallelogram, all of the properties of a parallelogram apply to the rectangle. Therefore, in a rectangle, opposite angles are congruent and 90o, consecutive angles are supplementary and its diagonals bisect each other.

There is one property that is special to a rectangle.  If the diagonals of a quadrilateral are congruent, then it is a rectangle.


*Note: All rectangles are parallelograms, but not all parallelograms are rectangles.

All of the properties that apply to a rectangle, can be used to find unknown quantities.  Be careful when determining which one to use.