A rhombus is a quadrilateral having all sides with unequal diagonals, which bisect each other.
Note: If a square is pressed from two opposite corners, the rhombus is formed.

Let  be a rhombus then its area can be evaluated in two ways:

(1) When one side and the include angle is given:
            Let one side be equal to “” with include angle. Since, the diagonal divides the rhombus into two equal triangle, therefore

(2) When two diagonal are given:
            Let  and  be the length of the diagonal  and  respectively and since, the rhombus is divided into four equal triangles, therefore

Example:
            The length of each side of a rhombus is cm and two of its opposite angles are  each. Find the area.
Solution:
            Given that each side,  and
            Area of the rhombus
                                              
                                             
                                               square cm

Example:
            The diagonal of a rhombus are m and m. Find its area.
Solution:
            Given that diagonal are m and m