Theory:

A rectangle is called a square whose adjacent sides are equal.
Now we are going to define a square \(ABCD\) as a quadrilateral is a rectangle whose sides are in the same measure.
 
Theory_4_1.png
 
Thus, if \(ABCD\) is a rectangle then \(AB = BC = CD = AD\) and \(AB || CD\) and \(BC || AD\).
 
Important!
Rhombus is a special case of kite. Note that the sides of a rhombus are all of the same length; this is not the case with the kite.
 
A rectangle has all the properties of a parallelogram.
In a square, the following properties are true:
  1. The opposite sides are parallel.
  2. All the four sides are in equal measure.
  3. The interior angles of the square is \(90°\).
  4. The diagonals are equal in measure and perpendicular bisector of each other.
  5. The adjacent angles are supplementary.