diagonals of rhombus are perpendicular
area is (1/2)*d1 * d2 where d1 and d2 are the diagonal lengths
draw the diagonals on your rhombus and you will see a 30-60-90 triangle and then figure
sides will be 6 , 6√3 . 12
so d1 is 2*6 = 12
and d2 is 2*6√3 = 12√3
and area = (1/2)*12*12√3
= 72√3 square cm.