### Theory:

A parallelogram with all sides are equal is called a rhombus.
Now we are going to define a rhombus $$ABCD$$ as a quadrilateral is a parallelogram with all the sides are in equal measures.

Thus, if $$ABCD$$ is a rhombus then $$AB = BC = CD = AD$$, $$AB || CD$$ 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 rhombus has all the properties of a parallelogram and also that of a kite.
In a rhombus, the following properties are true:
1. The sum of all the four angles of the rhombus is equal to $$360°$$.
2. The opposite sides are equal in length.
3. The opposite angles are equal in measure.
4. The adjacent angles are supplementary.
5. The diagonals are perpendicular bisector of each other.