### Theory:

A parallelogram whose each angle is a right angle is called a rectangle.

Thus, if \(ABCD\) is a rectangle then \(AB=BC=CD=AD\) and \(AB||CD\) and \(BC||AD\).

Important!

A rectangle has all the properties of a parallelogram with interior.

In a rectangle, the following properties are true:

- The opposite sides are parallel and equal in length.
- The interior angles of the rectangle is \(90°\).
- The diagonals are equal in measure and bisect each other.
- The adjacent angles are supplementary.