A parallelogram is a quadrilateral with two pairs of opposite sides parallel.
A rhombus is a parallelogram with equal sides
A square is a rhombus with all the angles equal (to 90°).
Students often make the mistake of defining a rhombus as
"A rhombus is a square pushed over."
It would be better to say that a square is a rhombus pushed up straight.
In a rhombus
All the sides are equal.
The opposite sides are parallel
The opposite angles are equal
The diagonals bisect each other at 90°
The diagonals bisect the angles at the vertices
there are 2 lines of symmetry
it has rotational symmetry of order 2
A square has all the properties of a rhombus, with more properties -
In a square:
All the sides are equal.
The opposite sides are parallel
The opposite angles are equal
All the angles are equal to 90°.
The diagonals bisect each other at 90°
The diagonals are equal.
The diagonals bisect the angles to give 45° angles
there are 4 lines of symmetry
it has rotational symmetry of order 4
A rhombus does NOT have all the properties of a square, therefore is not a special kind of square.